EASY THREE-BERRY CRUMBLE SLAB PIE

Steps:

• Preheat the oven to 375 degrees F (190 degrees C).
• Lightly dust an 11x15-inch half-sheet pan with flour. Carefully place the 2 pie crusts into the bottom of the sheet pan, gently stretching and trimming the crusts to fit the bottom and up the sides of the pan.
• Combine berries, sugar, arrowroot powder, and salt in a large bowl; stir well.
• Combine oats, flour, brown sugar, apple pie spice, and salt in a medium bowl. Use a pastry knife to cut butter into the oat mixture until butter is evenly distributed throughout and the crumble topping mixture resembles small, uneven pieces.
• Pour berry mixture evenly onto the crust and add crumble mixture on top.
• Bake in the preheated oven until brown and bubbly, 45 to 55 minutes. Remove and allow to cool for 30 to 45 minutes