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two squares of blueberry crumb bars stacked on top of each other

Oatmeal Blueberry Bars

4.97 from 31 votes
These oatmeal blueberry bars are made with a thick layer of oatmeal crust, a sweet bubbly layer of fresh blueberries, and topped with more cinnamon crumble. They're simple to make, great for meal prep, and the kids will love them as a wholesome breakfast or snack!
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Prep Time15 minutes
Cook Time55 minutes
Total Time1 hour 10 minutes
Servings: 16 bars

INGREDIENTS

Crust and Crumble Topping

  • 1 cup (2 sticks; 227g) unsalted butter melted
  • 2 cups (250g) all-purpose flour (gluten-free if needed)
  • 1 1/2 cups (150g) old-fashioned rolled oats (gluten-free if needed)
  • 1 teaspoons cinnamon
  • 1/2 teaspoon salt
  • 1 cup (200g) light brown sugar packed

Blueberry Layer

  • 16 ounces fresh blueberries
  • 1/4 cup granulated sugar
  • 2 Tablespoons fresh lemon juice (juice from 1/2 lemon)
  • 1 Tablespoon cornstarch

INSTRUCTIONS

  • Preheat the oven to 350°F and line an 8x8-inch metal pan with parchment paper.
  • In a large bowl, stir together the melted butter, flour, oats, brown sugar, cinnamon and salt. The mixture will be dry and sandy with some larger, well-formed crumble pieces. This makes up the crust and crumble. Set 1 heaping cup (I used almost 1 1/2 cups) of the mixture aside for the crumb topping.
    1 cup (2 sticks; 227g) unsalted butter, 2 cups (250g) all-purpose flour, 1 1/2 cups (150g) old-fashioned rolled oats, 1/2 teaspoon salt, 1 cup (200g) light brown sugar, 1 teaspoons cinnamon
  • Transfer the remaining crumb mixture to the prepared pan, and use a spatula or your fingers to press the mixture evenly into the bottom of the pan to create an even crust.
  • In the same or a separate large mixing bowl, add all ingredients for the blueberry layer and toss to coat the berries in the sugar and cornstarch. Dump the blueberries over the bottom layer.
    16 ounces fresh blueberries, 1/4 cup granulated sugar, 2 Tablespoons fresh lemon juice, 1 Tablespoon cornstarch
  • Sprinkle the reserved crumb topping over the blueberries. There will be blueberries still showing, this is what you want.
  • Bake in the preheated oven for 50-55 minutes, or until the crumble is golden and the blueberrries are bubbling around the edges. Check the bars with 15 minutes remaining and cover with foil if the top is starting to look to brown.
  • Allow the bars to cool for 30-60 minutes then use the parchment paper overhang to remove the bars and cool them completely. You can place them in the freezer to speed up the cooling process. Slice cooled bars into squares and enjoy.

Notes

Frozen Blueberries. I prefer fresh blueberries, but you can use frozen in a pinch— do not thaw. The bars will take longer to cook due to the increased liquid. 
Gluten-free: Use 1:1 gluten-free flour and gluten-free rolled oats.
Dairy free: Swap the butter or vegan butter or coconut oil.
Refined sugar free: Use coconut sugar instead of brown sugar and maple syrup instead of granulated sugar. 
Meal Prep: These can easily be a meal prep recipe! Kids love these in the morning, so follow the instructions to individually wrap each oatmeal crumble bar separately if you want to freeze them so they last longer.
Storage: Allow the bars to cool to room temperature and store any leftovers in an airtight container in the fridge for up to 5 days.
Freezer: Cut the bars into squares then wrap each one in plastic wrap. Place them in a freezer bag or airtight container and freeze for up to 3 months. Thaw overnight then warm in the microwave until warmed through.

Nutrition

Serving: 1bar | Calories: 271kcal | Carbohydrates: 38.1g | Protein: 3.1g | Fat: 11.8g | Cholesterol: 30.5mg | Sodium: 78.4mg | Fiber: 2.1g | Sugar: 18.2g | Vitamin A: 97.9IU | Vitamin C: 3.5mg
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