Blueberry Crumble Bars

Makes 12 servings

        Nonstick cooking spray
Crust:
8      tablespoons (1 stick) unsalted butter,
        room temperature and cut into
        4 pieces
¼     cup packed light brown sugar
2      tablespoons granulated sugar
1¼   cups unbleached, all-purpose flour
¼     teaspoon kosher salt
        Pinch ground cinnamon
Filling:
¼     cup granulated sugar
¼     cup packed light brown sugar
2      tablespoons tapioca starch
¼     teaspoon kosher salt
        pinch ground cinnamon
        pinch ground ginger
¼     teaspoon pure vanilla extract
4      cups fresh blueberries
Topping:
¾     cup unbleached, all-purpose flour
½     cup rolled oats (not quick cooking)
½     cup packed light brown sugar
¼     teaspoon ground cinnamon
¼     teaspoon kosher salt
6      tablespoons unsalted butter,
        cold and cubed

Nutritional information per bar:
Calories 282 (41% from fat) • carb. 39g • pro. 3g fat 13g • sat. fat 8g • chol. 35g • sod. 143mg calc. 4mg • fiber 2g

1. Lightly coat a 9-inch square baking pan with nonstick cooking spray and line with parchment paper; reserve.
2. Prepare the crust. Put the butter and sugars into a medium mixing bowl. Mix on Speeds 2 to 3 until creamy. Add the remaining crust ingredients and mix on Speed 2 until combined. Transfer the crust mixture into the prepared pan and press down firmly to pack into the bottom of the pan. Chill in refrigerator until firm.
3. While the crust is chilling, prepare the filling. Put the sugars, tapioca starch, salt, and spices in a large mixing bowl; mix on Speed 1 to combine. Add the vanilla extract and blueberries and stir until blueberries are well coated. Then mix on Speed 1 until about half of the blueberries have burst open, about 2 minutes. Reserve.
4. Put all of the topping ingredients, except for the butter, in a medium mixing bowl. Mix on Speed 1 to combine. Add the butter and mix on Speed 2 until large crumbs form.
5. Once the crust has sufficiently chilled, preheat oven to 350°F with the rack in the middle position. When the oven is preheated, bake until crust is firm and golden at the edges, about 20 minutes.Remove and spread filling on top of the hot, baked crust and return to the oven for an additional 15 minutes, or until bubbling at the edges. Cover evenly with the crumb topping and return to the oven for a final 15 minutes. The bars are done when the topping is evenly browned.
6. Cool completely prior to cutting and serving.