1 1/2 cups all-purpose flour
1/2 cup granulated sugar
1/2 teaspoon baking powder
Pinch salt
10 tablespoons unsalted butter cold and cut into cubes
1 large egg yolk
1 tablespoon cold water
For the Blueberry Filling:
2 cups fresh blueberries
2 tablespoons lime juice
2 tablespoons all-purpose flour
1/2 cup granulated sugar
1/4 teaspoon ground cinnamon
1 teaspoon vanilla extract
For the Crumble and Crust: Preheat the oven to 375 degrees F. Prepare a 8×8-inch baking pan with the non-stick coating of your choice. For the crumble and crust, whisk together flour, sugar, baking powder and salt. Next, cut in the cold butter using two forks or a pastry cutter then slowly mix in the egg yolk and cold water. Don't worry if the dough seems really crumbly. It should be! Next take half of the crumble mixture and press into the prepared pan. The rest should be saved for the top of the bars. For the Blueberry Filling: Stir together blueberries, lime juice, flour, sugar, cinnamon and vanilla until combined. To assemble, evenly add blueberry filling to top of crust. Next sprinkle the remaining crumble over the top of the blueberry filling. Bake for 30-38 minutes or until golden brown and set. Cool bars to room temperature then cut and serve.