To make the filling, place berries in a medium saucepan. Cook over medium heat, stirring often, until the berries are soft and tender, 8-10 minutes. Add the sugar and cornstarch to the berries, and bring to a boil. Cook an additional 1-2 minutes, or until thickened. Remove from heat and set aside.

Preheat the oven to 350 degrees and grease a 9x13 inch baking dish.

In a food processor, add all the ingredients for the crust and crumble topping. Pulse in 1-second intervals until the mixture resembles coarse crumbs. If you don't have a food processor, combine all ingredients using a pastry blender or two forks until all combined and resembling coarse crumbs. Reserve 1 1/2 cups for the topping, then press the rest of the mixture evenly into the bottom of the prepared baking dish.

Use a spoon to drop dollops of the berry filling over the crust, and use a spatula to spread the mixture over the entire surface.

Use your fingers to squeeze together clumps of the remaining crumble topping, and sprinkle evenly over the berry filling.

Bake until golden-brown, 30 to 35 minutes. Cool completely before slicing and serving, or serve cobbler-style by scooping with a spoon. Enjoy!