These blueberry oat bars are the perfect combination of buttery oat crumble and sweet, juicy blueberry filling. With a soft yet slightly crisp texture, they make a wonderful treat for breakfast, snack time, or dessert. Simple ingredients and easy steps make this recipe a reliable favorite for any occasion.

Why You’ll Love This Recipe

These blueberry oat bars are easy to prepare and require simple pantry staples. The oat crust doubles as a crumbly topping, saving you time and effort. The balance between the wholesome oats and the naturally sweet blueberry filling creates a comforting homemade flavor. They are perfect for meal prep, travel well, and can be enjoyed warm or cold. Plus, they’re versatile enough to customize with different fruits or flavor additions.

Ingredients

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

For the crust and crumble topping:
2 cups old-fashioned rolled oats
1 ½ cups all-purpose flour
1 cup light brown sugar, packed
½ teaspoon baking soda
½ teaspoon salt
1 teaspoon ground cinnamon
1 cup unsalted butter, melted

For the blueberry filling:
3 cups fresh or frozen blueberries
⅓ cup granulated sugar
2 tablespoons cornstarch
1 tablespoon lemon juice
1 teaspoon lemon zest
1 teaspoon vanilla extract

Directions

1. Preheat your oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving some overhang for easy removal.
2. In a large bowl, combine the rolled oats, all-purpose flour, brown sugar, baking soda, salt, and cinnamon.
3. Pour in the melted butter and mix until the mixture becomes crumbly and evenly moistened.
4. Press about two-thirds of the oat mixture firmly into the bottom of the prepared pan to form an even crust layer.
5. In another bowl, gently mix the blueberries, granulated sugar, cornstarch, lemon juice, lemon zest, and vanilla extract until well combined.
6. Spread the blueberry mixture evenly over the crust layer.
7. Sprinkle the remaining oat mixture evenly over the blueberry filling, lightly pressing it down.
8. Bake for 40–45 minutes, or until the top is golden brown and the filling is bubbling.
9. Remove from the oven and allow the bars to cool completely in the pan before slicing. This helps the filling set properly.
10. Lift the bars out using the parchment overhang and cut into squares.

Servings and timing

Servings: 12 to 16 bars
Preparation time: 15 minutes
Baking time: 40 to 45 minutes
Cooling time: 1 to 2 hours
Total time: Approximately 2 hours 15 minutes

Variations

You can substitute blueberries with raspberries, strawberries, or a mixed berry blend. For added texture, mix chopped almonds or walnuts into the crumble topping. If you prefer a slightly healthier version, replace half of the all-purpose flour with whole wheat flour. For extra sweetness and richness, drizzle a simple powdered sugar glaze over the cooled bars. Adding a pinch of nutmeg or cardamom can also give the bars a warm, aromatic twist.

Storage/Reheating

Store the bars in an airtight container at room temperature for up to 2 days. For longer storage, keep them in the refrigerator for up to 5 days.

To freeze, wrap individual bars tightly in plastic wrap and place them in a freezer-safe container or bag. They can be frozen for up to 3 months. Thaw overnight in the refrigerator before serving.

To reheat, warm a bar in the microwave for 15 to 20 seconds or in a 300°F (150°C) oven for about 5 to 10 minutes until heated through.

FAQs

Can I use frozen blueberries?

Yes, you can use frozen blueberries. There is no need to thaw them before mixing with the other filling ingredients.

How do I prevent the bars from becoming soggy?

Make sure to use the correct amount of cornstarch and allow the bars to cool completely before slicing to help the filling set properly.

Can I make these bars gluten-free?

Yes, substitute the all-purpose flour with a gluten-free flour blend and ensure the oats are certified gluten-free.

Can I reduce the sugar in this recipe?

You can slightly reduce the sugar in both the crust and filling, but keep in mind it may affect the texture and sweetness balance.

Why did my crumble topping turn out dry?

If the mixture seems too dry, ensure the butter was fully melted and evenly mixed throughout the oat mixture.

Can I make these bars ahead of time?

Yes, these bars are perfect for making a day in advance. Store them covered at room temperature or in the refrigerator.

How do I know when the bars are done baking?

The top should be golden brown and the blueberry filling should be visibly bubbling around the edges.

Can I add other fruits to the filling?

Yes, you can mix blueberries with raspberries, blackberries, or diced strawberries for a mixed berry version.

What size pan should I use?

A 9×13-inch baking pan works best for even thickness and proper baking.

Do I need to refrigerate the bars?

They can stay at room temperature for up to 2 days, but refrigeration is recommended for longer freshness.

Conclusion

Blueberry oat bars are a simple yet satisfying treat that brings together wholesome oats and vibrant blueberries in every bite. With their buttery crumble texture and sweet fruit filling, they are perfect for sharing with family or enjoying as a homemade snack throughout the week. Easy to customize and store, this recipe is one you’ll return to again and again.

Print