Delicious blueberry oatmeal crumble bars made with a buttery crust and crumble topping, fresh or frozen blueberries, and a hint of lemon. Perfect for a snack or dessert.
1: Preheat oven to 350F. Line an 8-inch square pan with aluminum foil and spray with cooking spray.
2: In a large microwave-safe bowl, melt the butter for about 1 minute on high power.
3: Add the flour, oats, sugars, and optional salt to the melted butter and stir to combine.
4: Set 1 heaping cup of the mixture aside for crumble topping.
5: Transfer the remaining mixture to the prepared pan and hard-pack it to create an even, smooth crust.
6: In a large mixing bowl, combine blueberries, granulated sugar, lemon juice, and cornstarch. Toss to combine.
7: Evenly distribute the blueberry mixture over the crust.
8: Sprinkle the reserved crumble topping mixture evenly over the blueberries.
9: Bake for about 55 minutes, or until edges are set and the center has just set.
