These homestyle crumb bars taste like blueberry crisp in bar form. The topping and crust is made from the same brown sugar-oat mixture. It’s sweet, crunchy and pairs perfectly with the blueberry filling.
And if you love blueberry desserts, give these easy blueberry muffins or blueberry galette a try.
Blueberry crumb bars are one of those dessert recipes that are both special and totally doable. They’ve got an irresistible buttery oat-based crust and topping sandwiching a layer of blueberry filling. The filling is the star of the recipe. It’s tangy, sweet, and packed with flavor, thanks to the lemon zest which adds a nice brightness to the bars.
And if you don’t have fresh blueberries on hand, frozen berries work great too! These bars are as simple to make as they are to eat.
Ingredients
There are two parts to this recipe. The oat crust/topping and the blueberry filling. Here’s what you need to make each one.
Oat Crust & Topping
- Oats. Old-fashioned oats are my preference for these bars. They add a nice flavor and texture. Don’t use steel cut oats. Those won’t work. If you’re gluten-free, use gluten-free oats.
- Flour. All-purpose flour holds the bars together.
- Sugar. Brown sugar adds a very subtle flavor to the crust. If you don’t have any in the house, use an equal amount of granulated sugar.
- Cinnamon. Ground cinnamon adds a nice flavor. You can also use pumpkin pie spice.
- Salt. Helps enhance all the flavors. Use table (fine) salt.
- Butter. A stick of cool butter is mixed into the oat-flour mixture. And cool is the key here. You want the butter to feel soft to the touch. This way it’s easy to mix into the other ingredients.
Blueberry Filling
- Blueberries. Fresh and frozen blueberries work in this recipe. If you use fresh blueberries, remove any stems and wash the berries before using them. For frozen blueberries, don’t let them thaw before using them. Simply use the blueberries from frozen.
- Sugar. A little granulated sugar adds sweetness.
- Cornstarch. We need the filling to thicken and cornstarch is perfect for this. Since cornstarch needs to reach 212℉ to thicken, make sure the filling bubbles.
- Lemon Zest and Juice. A little lemon zest and juice really help to bring out the flavor in the blueberry filling.
How to Make Blueberry Crumb Bars.
Step One: Make the Oat Mixture.
The crust and topping are made from the same easy-to-make streusel mixture.
- Whisk together the oats, flour, brown sugar, cinnamon, and salt. If there are any clumps of brown sugar, break them up with your hands. Add the cool butter.
- Cut the butter into the mixture until it’s crumbly.
- Remove about a cup of the mixture for the topping and set it aside. Press the remaining oat mix into a parchment-lined 8-inch square pan. It’s important to press the mixture firmly into the pan. This way, the crust won’t crumble apart when you cut the bars after they’re baked.
Step Two: Prepare the Filling and Assemble the Bars.
The filling is so simple to put together. Start with washed and dried fresh blueberries or frozen blueberries. If they’re frozen, don’t let the berries thaw. They get too juicy and can make the bars soft.
- Place the blueberries in a large bowl and add the sugar, cornstarch, lemon zest, and juice. Give this a good stir so that the blueberries are coated.
- Spread the blueberry filling over the crust.
- Sprinkle the reserved oat topping mixture all over the berries.
- Bake the bars until the filling bubbles and the topping is a light brown.
Serving and Storing
When the bars first come out of the oven, they’re very delicate. If you try to cut them right away, they can fall apart. Let the bars cool in the pan. Once they’re cool, lift the parchment or foil overhang and remove the bars from the pan. Place the bars on a cutting board and cut into squares.
Storage and Freezer Instructions.
Store your blueberry crumb bars in an airtight container in the refrigerator for up to 4 days. If you’d like to freeze them, let the bars cool. Then place in a freezer-safe container for up to 3 months. When you’re ready to eat, let them thaw in the refrigerator.
Blueberry Crumb Bars
Ingredients
For the Oat Crust and Topping
- 1 ½ cups old-fashioned rolled oats (4 ounces; 113 grams)
- 1 cup all-purpose flour (5 ounces; 142 grams)
- ½ cup brown sugar (3 ½ ounces; 100 grams)
- 1 teaspoon ground cinnamon
- ¼ teaspoon salt
- ½ cup butter, soft (4 ounces; 113 grams)
For the Blueberry Filling
- 2 cups blueberries, see note (1 pint)
- ¼ cup granulated sugar (1 ¾ ounces; 50 grams)
- 1 tablespoon cornstarch
- Finely grated zest of 1 medium lemon
- Juice of 1 lemon about 2 tablespoons
Instructions
Make the Oat Crust/Topping
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Preheat the oven to 350°F. Line an 8-inch square baking dish with parchment paper or aluminum foil, leaving a little overhang on all sides. (If you’re using parchment paper, you can clip it to the pan with binder clips. This holds it in place.) Grease the parchment or foil lightly with cooking spray; set aside.
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Place the oats, flour, brown sugar, cinnamon, and salt in a large bowl. Stir to combine. Break up any piece of brown sugar with your hands or a fork.
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Add the butter. Mix the butter into the oat mixture with a pastry cutter or your fingertips. The mixture should be crumbly and hold together when squeezed.
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Set aside 1 cup of the oat mixture in a small bowl. Press the remaining mixture into the bottom of the prepared pan. Be sure to press it firmly down.
Make the Filling.
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Place the blueberries in a medium bowl. Add the sugar, cornstarch, lemon zest and lemon juice and toss gently to combine. Spread the blueberries over the crust. Sprinkle the reserved crumb mixture over the blueberries. (Remove binder clips from pan now. They aren’t oven-safe.)
Bake the Bars
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Bake until the filling is bubbling and the top is golden-brown, about 45 minutes. Let cool at least 2 hours before cutting into bars.
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Store the bars covered in the refrigerator for up to four days or allow to cool and freeze for up to three months.
Recipe Notes
Blueberries.
Use fresh or frozen blueberries. If you’re using frozen blueberries, don’t allow them to thaw being using.
For extra filling, increase the blueberries in the filling to three cups.
Colleen says
I appreciate the way you give the ingredients in different denomination
Thank you from down under
Elizabeth says
You’re welcome!