Preheat the oven to 375°F. Line a 9x9-inch square baking pan with parchment paper and set aside.
Using a food processor or a mixing bowl with a pastry blender, mix together flour, powdered sugar, and salt. Add 8 tablespoons butter and pulse until it resembles cornmeal.
Lightly beat egg, then add to the processor/bowl and mix until a soft, crumbly dough forms. Dump dough into prepared pan and press evenly to cover bottom. Prick all over with a fork and bake for 8-10 minutes. Let cool slightly.
1 large egg
Meanwhile, combine raspberries and brown sugar in a medium bowl. Stir and mash the raspberries with the back of the spoon. Set aside.
12 ounces fresh raspberries, 2 tablespoons brown sugar
Make the topping: In a food processor or bowl, mix together flour, brown sugar, and granulated sugar. Pulse or cut in butter until coarse crumbs are formed.
1/3 cup all-purpose flour, 2 tablespoons brown sugar, 2 tablespoons granulated sugar, 2 tablespoons cold unsalted butter
Spoon raspberries with their juices over the top of the crust, making sure it covers the whole crust. Scatter on the crumble pieces.
Bake for 30 minutes, until golden brown. Let cool completely before cutting.
Notes
If using frozen raspberries in place of fresh, be sure to thaw completely and drain excess water before using.