- 1 cup all-purpose flour
- 1/2 cup light brown sugar
- 1/2 teaspoon baking powder
- 1/2 teaspoon ground cinnamon
- 1/4 teaspoon kosher salt
- 3/4 cup old-fashioned oats
- 1/2 cup (1 stick) unsalted butter at room temperature, cut into pieces
- Preheat oven to 375°F. Whisk flour, brown sugar, baking powder, cinnamon, and salt in a large bowl. Add butter and work into dry mixture with your fingertips until pea-sized lumps form. Add oats and mix with your fingertips until clumps form; it should look like crumb topping. Chill 15 minutes.
- Transfer mixture to a parchment-lined sheet tray and bake 8 minutes. Using a metal spatula, stir and toss crumble. Rotate tray and continue to bake until crumble is dark golden brown, about 8 minutes more. Let cool.