Blueberry Crumble Bars Recipe

Blueberry Oatmeal Crumble Bars

Crust and Crumble Topping
1 stick (1/2 cup) salted butter, melted
1 cup all-purpose flour
3/4 cup old-fashioned whole rolled oats (not quick or instant)
1/2 cup granulated sugar
1/4 cup light brown sugar, packed
pinch salt, optional, to taste

Blueberry Layer
12 oz. (2 cups) blueberries, fresh or frozen (don't thaw)
1/3 cup granulated sugar
2 Tablespoons lemon juice
2 teaspoons cornstarch

Preheat oven to 350F.  Line an 8-inch square pan with aluminum foil and spray with cooking spray.  Set aside.

Crust layer:  In a large microwave-safe bowl melt the butter.  Add the flour, oats, sugars, optional salt, and stir to combine.  Mixture will be dry and sandy with some larger crumble pieces.  Set 1 heaping cup of the mixture aside to be sprinkled on top later.

Transfer remaining mixture to prepared pan, and using a spatula or your fingers, hard-pack the mixture to create and even, smooth, flat crust.  Set aside.

Blueberry layer:  In a large mixing bowl, add all ingredients and toss to combine.  Evenly distribute blueberry mixture over crust.  Evenly sprinkle reserved topping mixture.  Before sprinkling, I squeeze the mixture in my palm to encourge bigger crumble pieces to form.  

Bake for about 55 minutes, or until the edges are set and the center has just set.  Crumble topping should appear set and very pale golden.  If using fresh, not frozen, berries, baking time may need to be reduced.

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 the bars before they are cool they will fall apart.  Bars will keep airtight at room temperature for up to 1 week, in the fridge for 10 days, or in the freezer up to 6 months.