These lemon blueberry crumb bars are simply the best! Made with a real blueberry pie filling sandwiched between two layers of soft, buttery, tender oat crumble! They are incredibly easy to prepare, totally customizable and absolutely delicious! They will definitely become your family's new favorite breakfast, snack and dessert!Recipe can be scaled up or down by using the slider if you hover your mouse over the number of Servings.
1 ½CupsAll Purpose Flour – spooned & leveled (SEE NOTES)
1CupLight Brown Sugar – packed
1tspEACH: Baking Powder & Cinnamon
1CupCold Butter – cubed (2 Sticks)
Optional for serving: Powdered Sugar, Cinnamon, Whipped Cream, Ice Cream, Honey, Lemon Glaze (SEE NOTES)
Preheat oven to 350 degrees Fahrenheit. Line a 9x13-inch baking dish with parchment paper, leaving an overhang on the sides of the pan (this will make it easy to lift the bars out of the pan). Set aside.
Prepare the filling: In a small saucepan, combine 3 cups of the blueberries, sugar, cornstarch, lemon juice and 1/8 teaspoon kosher salt. Place pan over medium-low heat. Cook, stirring frequently, for about 6-8 minutes, or until the berries start to soften and release their juices.
Increase heat to medium-high and bring to a boil while stirring constantly. Reduce heat to maintain a gentle boil and cook, stirring constantly, for 2 minutes, or until the mixture is thickened. Remove from heat.
Add in the remaining 2 cups blueberries, lemon zest and vanilla. Stir until everything is incorporated. Set aside and allow filling to cool completely.
Prepare crumble mixture: In the bowl of a food processor, add the oats, flour, sugar, baking powder, cinnamon and 1/8 teaspoon of salt. Pulse until the oats are mostly ground and ingredients are combined. Sprinkle the butter cubes evenly over the ingredients in the food processor. Pulse until the mixture resembles coarse crumbs. Add the vanilla extract and 2 tablespoons of water. Pulse until the mixture just begins to cling together and resemble a crumbly dough. Add another tablespoon of water if dough seems dry. (To test: Pick up a tablespoon of crumble dough. Squeeze the dough gently together – it should hold and cling together.)
Form crust and bake: Transfer half of the crumble dough (about 3 heaping cups) to the prepared baking dish. Use your hands or the back of a measuring cup to press it evenly and firmly into the bottom of the pan to form an even, smooth crust. (Tip: Dampen your hands or the back of the measuring cup with water to prevent sticking.)
Bake crust: Transfer to the oven and bake the crust for 10 minutes, or until lightly golden in color. Remove from oven.
Add blueberry filling: Evenly pour or spoon the cooled blueberry filling over the pre-baked crust.
Top with remaining crumble: Use your hands to sprinkle the remaining crumble dough evenly over the top of the filling.
Bake again: Return to the oven and bake for 35-40 minutes, or until the top of the blueberry bars are light golden brown in color.
Cool: Remove from oven and place the pan on a wire rack. Allow the bars to cool completely (at least 2-3 hours – SEE NOTES). Lift the cooled bars out of the pan using the parchment paper overhang on the sides. Slice into squares or bars.
Serve sprinkled with powdered sugar and enjoy!
Storage: Store completely cooled bars in an airtight container at room temperature for up to 5 days. Or, store in the fridge for up to 10 days, or freezer for up to 3 months.
Frozen fruit: You can use frozen berries! There is no need to thaw them first, however you may need to simmer the filling mixture for a little bit longer.
Lemon substitute: Don’t have lemon? Orange juice and zest is a delicious substitution!
Flour: It is important you measure your flour correctly! To properly measure flour, spoon the flour into your measuring cup, and then level it off. DO NOT just dip the measuring cup into the container of flour.
Gluten-free: Use gluten-free oats and flour
Vegan: Use vegan butter and ensure your brand of sugar is vegan-friendly or use vegan sugar substitutes. (See post for full list of suggestions)
To quickly cool: You can allow the bars to cool completely at room temperature. Or, you can allow the bars to cool at room temperature for one hour, then transfer pan to refrigerator to speed up the process.
Warning on slicing bars: If you try to slice the blueberry bars while they are still warm, and before they have cooled completely, they will fall apart. You can enjoy them while warm, just be prepared to serve them in a bowl and eat them with a spoon. I suggest topping them with a scoop of ice cream!!
Half batch: You can easily half the recipe and bake in a parchment paper lined 9-inch baking pan. You will need to slightly adjust the baking time – it will be shorter. Use a toothpick to test for doneness if needed.
Lemon Glaze: To make glaze, whisk together 1 cup of powdered sugar with 2 tablespoons of lemon juice. Taste and adjust with an additional tablespoon of lemon juice or a milk if a thinner glaze is desired. Drizzle on cooled bars.
Nutritional information is an approximation based upon 24 servings. Exact nutritional information will depend upon the brands used and your precise measurements.