Marshmallow Chocolate Chip Cookie Bars

A stack of four thick blondie bars with chocolate chips and white chocolate chunks, with a bite taken out of the top bar.

5 from 6 votes

Marshmallow Chocolate Chip Cookie Bars

🍪🍫 If you like chocolate chip cookies or s'mores, you're going to LOVE these EASY cookie bars! Fast, no-mixer, a family FAVORITE with kids and adults alike! Great for casual entertaining, birthday parties, potlucks, and more. Tip: If you want to make a half-batch, use an 8x8-inch pan and bake for about 25 minutes.

Prep Time10

Cook Time27

Course: Bars & Blondies, Dessert

Cuisine: Dessert

Keyword: blondies with chocolate chips, chocolate chip cookie bars, chocolate chip cookie bars with marshmallows

Servings:

Calories: 320cal

Equipment

Ingredients

1 cup unsalted butter melted
2 large eggs
2 cups light brown sugar packed
1 tablespoon vanilla extract or to taste
2 cups all-purpose flour
2 teaspoons cornstarch optional (creates a softer texture)
1 teaspoon salt or to taste
1 heaping cup mini marshmallows
1 cup semi-sweet chocolate chips or another type of baking chip, see the FAQs in the blog post
½ cup caramel chips (I get mine from Trader Joes and use a heaping 1/2 cup you can use another type of baking chip or solely chocolate chips if desired

Instructions

Preheat oven to 350F and spray a 9x13-inch baking pan very well with cooking spray. Tip - Optionally, for easier cleanup, use a thick, heavy duty aluminum foil to line your pan and spray with cooking spray. Do not use cheap foil, it will just rip and create a mess.
To a large, microwave-safe bowl add the butter and heat to melt, about 1 minute on high power to start, then heat in 15-second bursts until it's melted.
Wait momentarily before adding the eggs so you don’t scramble them. Add the eggs, brown sugar, vanilla, and whisk until smooth.
Add the flour, optional cornstarch, salt, and stir until just combined; don’t overmix.
Add the marshmallows, chocolate chips, caramel chips (or whatever baking chips you're using; aim for about 1 1/2 cups in total) and stir to combine.
Turn the batter out into the prepared pan. Important Marshmallows Tip - Make sure that the marshmallows are covered by batter. Exposed marshmallows will burn! Push them down with your finger so they're nicely submerged into the batter, or using a spatula, make sure there's a bit of batter on top of them because they'll burn otherwise. If you want extra chocolate, sprinkle a few extra chocolate chips over the top.
Bake for about 26 to 28 minutes, or until done. A toothpick should come out clean, or with a few moist crumbs but no gooey batter. Baking Tips - I strongly recommend rotating your pan once midway through the baking time to ensure even browning of the top surface of the bars. Start checking early, just to make sure nothing is browning too quickly. Highly unlikely, but if the top surface or any marshmallows are looking too dark before you know the bars will be cooked through in the center, drape a sheet of foil over the entire baking pan to tent it.
Allow the bars to cool in the pan for about 30 minutes, or as desired, before slicing and serving. Note - Marshmallows are really just sugar + air. Therefore, it's not unusual for them to deflate or almost 'disintegrate' into nothing during the baking and subsequent cooling process. This is completely normal. To combat it, or still give the look of marshmallows, you can sprinkle some of top of the bars as they cool. This is a causal dessert and I urge you to think of it as such.

Notes

Storage: Recipe will keep airtight at room temp for up to 5-7 days. I do not store it in the fridge. You could potentially freeze it for up to 3-4 months, although I have not tested that.

Nutrition