Triple Peanut Butter Monster Cookie Bars

I make my fair share of treats, and have the hodgepodge of random add-ins in my pantry to show for it.

Half-used bags of chocolate chips, peanut butter chips, and a random assortment of candy were taking over the cupboard so I found a home for them.

Triple Peanut Butter Monster Cookie Bars - Soft, gooey bars loaded with M&Ms, chocolate and made for serious peanut butter lovers! So good!

In these bars.

They’re the perfect bar to toss in everything but the kitchen sink.


Triple Peanut Butter Monster Cookie Bars - Soft, gooey bars loaded with M&Ms, chocolate and made for serious peanut butter lovers! So good!

Use this flexible and forgiving dough base as your opportunity to stir almost anything that’s plaguing your pantry into it.

What else are you going to do with 1/3 cup chocolate-covered sunflower seeds from your last Trader Joe’s impulse buy or that small handful of butterscotch chips from your last batch of cookies, or a few stray marshmallows.

Use up last year’s Halloween candy or Easter candy. Those Fun-Size Twix bars are begging to be diced and tossed in. Don’t pretend you don’t discover random candy from months ago. Well, I do. Life of a food blogger.

Triple Peanut Butter Monster Cookie Bars - Soft, gooey bars loaded with M&Ms, chocolate and made for serious peanut butter lovers! So good!

The bars come together in 5 minutes in one bowl, no mixer needed. Unlike making cookies, there’s no dough to chill, and they’re ready in under 30 minutes from start to finish.

I used my go-to blondie base, with a half-cup peanut butter stirred in, before stirring in the kitchen sink.

Triple Peanut Butter Monster Cookie Bars - Soft, gooey bars loaded with M&Ms, chocolate and made for serious peanut butter lovers! So good!

I had partially used bags of Peanut Butter M&M’s, peanut butter chips, chocolate chips, chocolate chunks, toffee bits, and included them all.

Because peanut butter is used three times – peanut butter that’s stirred into the dough, Peanut Butter M&Ms, and peanut butter chips – they pack a bold, peanut buttery punch.

Triple Peanut Butter Monster Cookie Bars - Soft, gooey bars loaded with M&Ms, chocolate and made for serious peanut butter lovers! So good!

They’re very moist and soft. The edges turn slightly chewy, while the interior remains a squishy, soft heaven.

The crunchy candy coating of the M&Ms and their firmness, coupled with Heath toffee bits, are the perfect texture contrast to the buttery, peanut buttery, dense, melt-in-your mouth dough.

Triple Peanut Butter Monster Cookie Bars - Soft, gooey bars loaded with M&Ms, chocolate and made for serious peanut butter lovers! So good!

There’s plenty of chocolate, too. Chocolate and peanut butter just go together. The abundance of melted chocolate chips is practically mandatory with all that peanut butter.

Soft, chewy, fast, easy, peanut butter used three times, and you can clean out your cupboards. That’s success.

Triple Peanut Butter Monster Cookie Bars - Soft, gooey bars loaded with M&Ms, chocolate and made for serious peanut butter lovers! So good!

And let’s face it, any time you can bake candy into a dessert, you won’t hear too many complaints.

Cleaning out your pantry never tasted so good.

Triple Peanut Butter Monster Cookie Bars - Soft, gooey bars loaded with M&Ms, chocolate and made for serious peanut butter lovers! So good!

Triple Peanut Butter Monster Cookie Bars - Soft, gooey bars loaded with M&Ms, chocolate and made for serious peanut butter lovers! So good!

Triple Peanut Butter Monster Cookie Bars

Peanut butter is used three times in these dense, rich, moist, fast, and easy bars. There’s peanut butter stirred into the dough, Peanut Butter M&Ms, and peanut butter chips, so the bars pack a bold, peanut buttery punch. There’s plenty of chocolate, the perfect compliment to all that peanut butter. Use the dough base as a blank canvas and start cleaning out your pantry – butterscotch or white chocolate chips, nuts and seeds, dice old holiday candy and toss it in. Mix and match with the add-ins you have on hand rather than buying new. Cleaning out your pantry never tasted so good.


1/2 cup unsalted butter (1 stick), melted
1 large egg
1 cup light brown sugar, packed
1 tablespoon vanilla extract
heaping 1/2 cup creamy peanut butter (use Jif, Skippy, etc.; don’t use homemade or natural – too runny)
1 cup all-purpose flour
1 cup Peanut Butter M&Ms (or Peanut, Plain, or favorite variety)
3/4 cup semi-sweet chocolate chips or chunks, or a combination
1/2 cup Reese’s Peanut Butter Chips
1/3 cup Heath Bar Toffee Bits


  1. Preheat oven to 350F. Line an 8-by-8-inch baking pan with aluminum foil, spray with cooking spray; set aside.
  2. In a large, microwave-safe bowl melt the butter, about 1 minute on high power.
  3. Wait momentarily before adding the egg so you don’t scramble it. Add the egg, brown sugar, vanilla, and whisk until smooth.
  4. Add the peanut butter and whisk or stir until smooth and incorporated.
  5. Add the flour and stir until just combined, don’t overmix.
  6. Add all remaining add-ins and fold to incorporate.
  7. Turn batter out into prepared pan, smoothing the top lightly with a spatula. I like to strategically place a few M&Ms on the top of the batter for a nice visual effect.
  8. Bake for about 25 minutes, or until top is set. A toothpick inserted in the center should come out clean, or with a few moist crumbs, but no batter. Allow bars to cool in pan for at least 30 minutes before slicing and serving. Bars will keep airtight at room temperature for up to 1 week, or in the freezer for up to 6 months.

Recipe from Averie Cooks. All images and content are copyright protected. Please do not use my images without prior permission. If you want to republish this recipe, please re-write the recipe in your own words, or simply link back to this post for the recipe. Thank you.

Only Eats

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What’s the last pantry cleanout recipe you’ve made? What do you put in your Monster Bars?

157 comments on “Triple Peanut Butter Monster Cookie Bars”

  1. These look perfect! Loaded and perfect!

  2. I am trying to eat healthy during the weeks leading up to my wedding, but looking at this is making that a whole lot more difficult haha. They sound DELICIOUS! And I’m so glad you liked the Saint Paul post, I had an amazing time there and was just awestruck by the beauty while I was flying over the state. I definitely want to get back there to do some hiking!

    • I adored the post. Such a trip down memory lane – college, my family, my childhood. Thank for posting it and glad that MN was better than you thought it was going to be. If it wasn’t for the winters, it really is a wonderful place!

      And congrats on your upcoming wedding!

  3. You must know how much I love these cookies, they are fabulous! Thanks for linking up with What’s Cookin’ Wednesday!

  4. Hi,
    I just wanted to say that every recipe I’ve made of yours is wonderful! And these are possibly the best! I used your base, then added chocolate chips, white chocolate chips, sliced almonds, peanut butter cups, and marshmallows! So much for eating healthy for cross country, haha! But you are a very good baker and I plan to make most if not all of your recipes!

    • Thanks for LMK you’ve tried other recipes and these are your new fave! All your add-ins sound great! If I would have had any PB cups, I would have used those, too! Mmm, marshmallows – I bet they were a little bit like PB smores! If you try other recipes, please come back and LMK how it went!

  5. I, too, am the Queen of The Freezer Full of Mismatched Quarter-full Bags of Candy, Nuts, and Other Miscellany! I do this all the time with cookies – just throw in everything. But from the looks of it, I am missing out by not using your bar base here, though. It looks divine.

  6. Pinning…these look FABULOUS!! Thanks for sharing! =)

  7. Outdoing yourself every time–I feel like I might be tempted to lick the kitchen sink after this, yick! :) thanks for sharing, Averie!

  8. Wow!! These were amazing!!! Thank you so much for sharing this great recipe!!

  9. Oh WOW! These bars look intense :) I can’t wait to taste this

  10. I made these once and they were delicious!! …but I’m a fan of the orignal monster cookie so do you think you could substitute old fashioned oats for the flour? If so, would it be a 1:1 ratio of flour to oats?

    • If you’re talking cookies vs. bar cookies, it’s not that easy to just ‘swap’. This recipe was written to make these to be pressed into a pan, not baked as actual cookies and b/c there is no baking soda or baking powder, they would likely spread thin and flat and not work. If you wanted to use some oats in these bars, feel free to add a cup or so, and reduce the flour by maybe 3/4 cup.

      If you’re looking for oatmeal cookies, I have at least a half dozen really solid oatmeal cookie recipes. Browse and then add your favorite add-ins to whichever base you choose.

      • Sorry I wasn’t clear. I still want to make bars but i wasnt sure if it would work to use oats instead of flour. I will try adding 1 cup of oats and taking out 3/4 cup of flour. Thank you so much for your quick response! Very impressive

  11. I think these sound and look incredibly delicious- but I have to say, I’m not sure how anyone has peanut butter M&M’s just left over without eating them. That never happens around here! :)

  12. I would like to contribute the recipe for the cookie bars to our newest church cookbook. I made them for our homeschool back to school bash. I put them in my Longaberger bread basket and renamed them: “Schoolbox Brownies” – the colors reminded me of a child’s crayon box!

    The bars were devoured, of course!

    I would like permission to submit this great recipe! I would not be using any images.


    Sarah Carroll

  13. Hi there…I made these bars yesterday and they are DELICIOUS! I had one problem though…they were very greasy/buttery on the bottom. I put them back in the oven thinking they weren’t quite done. Do you think they’d come out the same if I used less butter next time? Or maybe margarine? I served them with a paper towel on the platter and that helped to soak up some of the butter. Any suggestions will be appreciated. I’m definitely going to make these again! : )

    • Greasy..hmm, could have been the type/brand of PB used. I used Jif in mine. Or could have been the butter. You could reduce either the Pb or the butter, slightly, maybe 2 tbsp or so if you wanted. Or you could add maybe 2 to 4 tbsp more flour. Or you could bake them slightly longer. However, they’re not exactly a ‘light’ treat so some grease is normal :) But sounds like you would benefit most from slightly more flour. Lmk what you do when you remake them and how it pans out!

  14. I have these in the oven as we speak! They look awesome and the dough was delicious! ;-) I agree that they were very greesy. I added 1.5 cups flour instead of just one. Hope they turn out! They look like they will!

  15. These were packed full of peanut buttery goodness.. Thanks for this.. I made this one weekend with my God-Child and we had a blast making as well as eating..

  16. I made a version of these to give as a birthday gift – they were fab! Have just written about them here –

    Thanks for the recipe! :)

  17. Yumm! The fourth recipe I’ve tried of yours, and just like the other three, it turned out excellent! I loved how easy it was, and it was a great way to get rid of leftover old candy. I did have to leave it in the oven for an extra ten minutes or so before it was done, but other than that this turned out great. Thank you for another great recipe!!

    • So glad you were able to clear out some random candy and that you’re batting 4 for 4 with my recipes – love that! And yes, baking time is variable based on candies used and just how loaded up they were, oven variances, etc. So glad you’re enjoying them!

  18. These are DANGEROUS. So easy, so yummy, and so addictive! Your recipes are so tempting to make because they come together so well and are scrumptious but I have to get them out of the house the next day or I’d eat the whole batch!

    • Thanks Erica for trying these and for the sweet compliments about my recipes and being easy and user-friendly. I try really hard with that and glad it’s working for you! And yes, I have to re-home and donate most of what I make, too – or I wouldn’t be able to fit thru the door. LOL

  19. Woah, woah, woah, these look amazing. Everything looks so melty and moist. Pinned, and now I have to try ASAP!

  20. Awesome as always! Loved these so much. I used a full bag of peanut butter egg shape m&m’s from Easter as the mix in and left out the peanut butter chips and toffee bits since I didn’t want to create more partial bags of things. I also needed to use up the m&m’s. The peanut butter ones are my favorite and any left unused would be eaten – not that a few weren’t used for quality control while baking. Super soft, dense, delicious. Would make again exactly the same, but yet I want to try other combinations and exactly as written. I’m sitting here now trying to think if I make another batch today who can I take them to so I don’t eat them all. I know I’ve commented before, but it is worth repeating that you make winner recipes.

    • Deb thanks for taking the time to comment again and so glad you loved these bars and want to make them again (and again!) and use up your candy stash. They’re a great pantry clean-out bar :) Glad you’re happy & thanks for the praise about my winner recipes!

  21. good

  22. هنا

  23. Can your recipes be doubled and baked in a 9×13 pan instead of 8×8 or 9×9? Our family is getting together and the 25 of us looooove sweets! I have literally spent the past 3 days looking at recipes on your site and am having the hardest time deciding on just one!

    • Most recipes yes can be doubled to bake as a 9×13 rather than an 8×8. Most of them I don’t personally test that way because I bake 5-7 days a week for a very small family and don’t need the excess but in theory, it should work; and many readers do double and write in to say it works fine. LMK what you end up making and how it goes!

  24. Do you have any suggestions for high altitude baking??

  25. HELP! I was planning to make this recipe for a bake sale, but I accidentally mixed the flour and the brown sugar together instead of mixing the brown sugar with the melted butter! They’re mixed really well together, there’s no going back. I really don’t want to throw out and waste the ingredients (especially since I used pricey organic brown sugar). Can I still proceed with the recipe? If not, are there any other recipes I can use the flour/brown sugar mixture for?

    • So you mixed a cup of brown sugar with a cup of flour? At this point if you haven’t already carried on with the rest of the recipe, I would toss it and start over. I wouldn’t continue on, knowing you’re going to put more $$ ingredients in, knowing full well you’ve already screwed up…that would guarantee then everything is going to be a mess in the final analysis. You should cut your losses now.

      Generally flour and sugar don’t go together unless you’re making a streusel topping at which point you’d cut in butter. You could make these or something along these lines…

  26. HI!

    I’m wondering if I can make these Triple Peanut Butter Monster Cookie Bars in a 13×9 pan?


  27. Can I use this recipe but make balls and cook into cookies instead of bars?

  28. So I was scrolling through your cookie recipes, looking for a way to use up the ridiculous amount of Valentine’s candy my kids have been given, when lo and behold, I found this recipe–great for using up add-ins AND in bar form–my fave. SO good! I don’t think I’ve tried your PB bar cookies before. These turned out thick so I made them into 18 triangle cookies and still feel like it’s a generous amount.

    • Thanks for trying the recipe and I’m glad it came in handy so you could use up the V-Day candy! I generally do variations on this theme right after Halloween :) I am impressed you got 18 triangle cookies out of the batch and still feel like it’s a generous amount! That’s great to hear!

  29. I followed the recipe exactly, and these were AMAZING (and easy!). I made them for Easter with the pastel M&Ms and my family went crazy. My dad said he loved that every single bite had a fun surprise. I would definitely make these again, but I might not bother with the toffee bits, unless of course I had them hanging around anyway!

  30. Hi there — I just have to tell you, I made these for Easter AND THEY ARE SOOO GOOD!!  I made a slight variation, and posted them on my blog today…

    Thank you SO much for sharing this goodness, can’t wait to make more from your blog soon :)

  31. I have these in the oven right now :)

  32. These bars are now requested every time my friends get together.  They are delicious.  I love your blog. :)

  33. Thank you for making my coworkers think I’m the best baker ever! This is such a wonderful recipe (and base blondies recipe) that I get requests all the time. 

  34. Hi there! Thanks for the delicious looking recipe! I’m going to try baking it this weekend, however, I notice there is no baking soda OR baking powder called for. I’ve never baked a bar cookie without using one or the other. I’ve always been under the impression that using non baking powder/soda will cause them to turn out flat and tough, no?

    • I do not like cakey bars cookies at all and when I put leaveners in them, even 1/2 teaspoon, they turn out cakier than I like. If I wanted cake, I’d make cake :)

      The bars, if you make them according to the recipe, should look like the photos. They’re definitely not tough and I wouldn’t say flat either but it’s personal preference.

  35. I made these this weekend! They turned out great (although I think I overbaked them a little).
    Can’t wait to try more recipes from this site!

  36. Can you make ahead and freeze?

  37. Hi,

    Do you think these could be made with double the peanut butter chips and no M&M’s?  I love them, but a jaw problem make it impossible to indulge.

    Thank you.

  38. Sounds delicious! I often keep leftover candy in the freezer and will just chop up whatever I have left to add to cookie or brownie recipes. Pinned.

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