Blueberry crumb bars

• 3 cups (390g) all-purpose flour (spoon and level)
• 1/2 cup (100g) granulated sugar
• 1/2 cup (100g) brown sugar
• 1 tsp baking powder
• 1/4 tsp salt
• 1 large egg
• 1 1/2 tsp vanilla extract
• 1 cup (226g) unsalted butter, chilled and cut into cubes

• 1 Tbsp (9g) cornstarch
• 1/2 cup (100g) granulated sugar
• 1 1/2 Tbsp (22ml) lemon juice
• 4 cups (538g) fresh blueberries, at room temperature

• Preheat oven to 375 degrees F. Butter a 9x13-inch baking dish (also line with parchment and butter parchment if you'd like to lift them out easier), set aside.
• In a large mixing bowl whisk together flour, 1/2 cup granulated sugar, brown sugar, baking powder and salt.
• In a small mixing bowl, whisk together egg and vanilla until combine.
• Add egg mixture and cold butter cubes to flour mixture and using a fork or a pastry cutter, cut mixture together until it resembles coarse crumbs.
• Press 1/2 of the mixture evenly into prepared baking dish.
• In a separate mixing bowl, whisk together remaining 1/2 cup granulated sugar and cornstarch, stir in lemon juice.
• Add blueberries then toss mixture to evenly coat, pour and spread coated blueberries evenly over crust in baking dish.
• Sprinkle remaining crumb mixture over berry layer.
• Bake in preheated oven about 38 - 42 minutes until top is golden brown.
• Allow to cool for about 20 - 30 minutes before cutting into squares.
• Store cooled bars in an airtight container in refrigerator (rewarm in microwave for 10 - 15 seconds if desired).