Blueberry Oatmeal Crumble Bars

Blueberry Bars with Oatmeal Crumble Topping — These bars are buttery and packed with blueberry flavor! They take just 10 minutes of prep and then go straight into the oven. So easy to make, and a crowd pleaser every time!

Easy Blueberry Oat Bars Recipe

I was going to call these blueberry breakfast bars. Or blueberry snack bars. But anytime you feel like eating juicy blueberries with buttery oat crumbles is the kind of bar they are.

This blueberry crumble bars recipe is an easy, one bowl, no mixer recipe that takes just minutes to make. I adapted the recipe from my Blueberry Pie Bars by reducing some of the flour and adding oats to the crust and crumble mixture. The oats add such great texture.

The crust and oatmeal crumble topping are one and the same. Love it when that happens so there’s one less step and one less bowl to wash! 

I also eliminated the Greek yogurt, sugar, and egg from the filling and kept the focus on the blueberries.

The blueberry oatmeal bars aren’t overly sweet and the blueberry flavor shines beautifully, which is why they’re great for breakfast, brunch, snacks, or a healthy dessert. They’re soft and tender, yet slightly chewy from the oats, and I’m a sucker for anything with a crumble topping.

My daughter said they’re one of the best ‘desserts’ I’ve made in a long time. I made these blueberry bars on a Sunday and had breakfast ready to grab-and-go for her for the week.

One less thing to worry about on busy weekday mornings! Loved that.

What’s in the Blueberry Bars? 

To make the blueberry oatmeal bars, you’ll need: 

  • Unsalted butter
  • All-purpose flour
  • Old-fashioned oats
  • Granulated and brown sugar
  • Salt
  • Blueberries
  • Lemon juice
  • Cornstarch 

Should I Use Fresh or Frozen Blueberries? 

I used frozen blueberries for these blueberry crumble bars, but I’m sure fresh would work as well.

If you’re using fresh blueberries for these bars, I recommend reducing the bake time by 10 to 15 minutes (I haven’t made this recipe with fresh berries, so I can’t say for certain). When evaluating the doneness of your bars, it’s more important to decide based on how the bars look rather than how much time has passed. 

Can I Use Instant Oats? 

Don’t use quick cook or instant oats because they’re finer than old-fashioned oats and behave like flour. Instant oats will make mixture too dry. 

How to Make Blueberry Bars

You’ll first need to make the buttery oatmeal crumble topping. To do so, melt the butter in a large bowl before adding in some flour, oats, two types of sugar, and salt. Stir all of that together. Note that the mixture should be dry and sandy at this stage. 

Set some of the mixture aside to be sprinkled on later as the oatmeal crumble topping, then transfer the rest to a greased 8×8-inch baking pan. Pack the mixture into the pan with your hands or a spatula (just make sure it’s packed down into an even layer and covers the entire pan). 

Once the crumble topping and crust have been made, move on to the blueberry filling. In the same bowl you made the topping in, add some blueberries, cornstarch, lemon juice, and sugar. Toss to combine, then spread the blueberry filling over the crust. 

Sprinkle the reserved crumble topping over the blueberry layer before popping the blueberry bars into the oven. Bake the bars until the edges are set and the oatmeal crumble topping is just turning golden. 

Tips for the Best Blueberry Bars

I made this recipe in a 8×8-inch pan, but you should be fine to double the recipe and bake the blueberry crumble bars in a 9×13-inch dish. 

I should note that you can’t eat these bars straight out of the oven. These blueberry bars need time to cool and set (around 30 minutes or so). If you try to cut into the bars right away, they’ll fall apart in your hands and will likely scald the roof of your mouth. 

These bars freeze incredibly well and will last up to six months if sealed tightly in a freezer bag or freezer-safe container. So go ahead and make a pan or two of these bars when blueberries are in season and thaw them out when you have guests coming over! 

Yield: 8 servings

Blueberry Bars with Oatmeal Crumble Topping

Prep Time 10 minutes
Cook Time 55 minutes
Cooling Time 30 minutes
Total Time 1 hour 35 minutes

These Blueberry Bars with Oatmeal Crumble Topping are buttery and packed with blueberry flavor! They take just 10 minutes of prep and then go straight into the oven. So easy to make, and a crowd pleaser every time! 

Ingredients

Crust and Crumble Topping

  • 1/2 cup (1 stick) unsalted butter, melted
  • 1 cup all-purpose flour
  • 3/4 cup old-fashioned whole-rolled oats (don’t use quick cook or instant, they’re finer and behave like flour and will make mixture too dry)
  • 1/2 cup granulated sugar
  • 1/4 cup light brown sugar, packed
  • pinch salt, optional and to taste

Blueberry Layer

  • 12 ounces (2 cups) blueberries (fresh or frozen; I used frozen and didn’t thaw)
  • 1/3 cup granulated sugar
  • 2 tablespoons lemon juice
  • 2 teaspoons cornstarch

Instructions

  1. Preheat oven to 350F. Line an 8-inch square pan with aluminum foil and spray with cooking spray; set aside. Lining the pan helps with cleanup and is recommended.

Make the Crust and Crumble Topping

  1. In a large, microwave-safe bowl melt the butter, about 1 minute on high power.
  2. Add the flour, oats, sugars, optional salt, and stir to combine. Mixture will be dry and sandy with some larger, well-formed crumble pieces.
  3. Set 1 heaping cup mixture aside to be sprinkled on later as crumble topping.
  4. Transfer remaining mixture to prepared pan, and using a spatula or your fingers, hard-pack the mixture to create an even, smooth, flat crust; set aside.

Make the Blueberry Layer

  1. In a large mixing bowl (same one used for crust and crumble is okay), add all ingredients and toss to combine. If sugar hasn’t dissolved fully that’s okay because it liquifies while baking.
  2. Evenly distribute blueberry mixture over the crust.
  3. Evenly sprinkle with the reserved heaping 1 cup crumble topping mixture. Before sprinkling, I squeeze the mixture in my palm to encourage bigger crumble pieces to form.

Bake the Bars

  1. Bake for about 55 minutes, or until edges are set and center has just set. Crumble topping should appear set and very pale golden. I used frozen berries without thawing and the pan was very cold going into the oven. If using fresh berries, baking time will be reduced, but I’m not sure by how much, I’d guess at least 10-15 minutes, possibly less. Bars may take longer than 55 minutes if blueberries are very juicy. Watch your bars, not the clock, when evaluating doneness.
  2. Place pan on a wire rack and allow bars to cool for at least 30 minutes before slicing and serving. If you try to slice bars before they’ve cooled completely, they’ll be extremely messy and could fall apart. Bars will keep airtight at room temperature for up to 1 week, in the fridge for up to 10 days, or in the freezer for up to 6 months.

Notes

Nutrition Information:

Yield:

8

Serving Size:

1

Amount Per Serving: Calories: 414Total Fat: 12gSaturated Fat: 7gTrans Fat: 0gUnsaturated Fat: 4gCholesterol: 31mgSodium: 22mgCarbohydrates: 62gFiber: 2gSugar: 33gProtein: 4g

More Blueberry Dessert Recipes: 

ALL OF MY BLUEBERRY RECIPES!

Blueberry Pie Bars — Super soft, easy bars with a creamy filling, streusel topping and abundance of juicy blueberries.

Blueberry Crisp — The sweet juicy blueberries contrasted with the crispy and crumbly oat-based topping is just perfect!

Crustless Blueberry Pie – A FAST, crustless, no-mixer dessert that’s perfect for summer entertaining, picnics, or potlucks!! Somewhere in between pie, cake, and blondies is what you get with this FABULOUS blueberry dessert recipe!

Lemon Blueberry Bundt Cake with Lemon Glaze — Almost more berries than cake in this soft, fluffy lemon blueberry bundt cake! The lemon glaze is plate-licking delish!!

Lightened Up Blueberry Lemon Pound Cake — The blueberry-lemon combo is always a win, and so is pound cake that won’t break your caloric piggybank. This Lemon Blueberry Pound Cake is a keeper!

Blueberry Muffin Cake — This fast and easy cake tastes like a big buttermilk pancake that ran into a blueberry muffin on the way to the oven.

Blueberry Zucchini Bread— This blueberry zucchini bread is a quick, no-mixer recipe that’s sweet, but not too sweet. Each bite is bursting with fresh blueberries!