Preheat your oven to 350°F. Grease an 8x8-inch baking dish with cooking spray or butter.
In a mixing bowl, whisk together the flour, brown sugar, baking powder, cinnamon, cloves, and ginger.
2 cups all-purpose flour, ¾ cup brown sugar, 1 Tablespoon baking powder, 1 teaspoon ground cinnamon, ¼ teaspoon ground cloves, ¼ teaspoon ground ginger
Create a well in the center, then add the pumpkin purée, vegetable oil, and milk. Stir until smooth and fully combined.
1 cup pumpkin purée, ½ cup vegetable oil, ¼ cup whole milk
Pour the batter into the prepared baking dish and smooth the top.
In a separate bowl, mix flour, brown sugar, and cinnamon. Cut in the cold butter using a pastry cutter or knife until the mixture resembles coarse crumbs. Sprinkle the crumble evenly over the batter.
¾ cup all-purpose flour, ¾ cup brown sugar, 2 teaspoons cinnamon, ½ cup unsalted butter
Bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs.
Let cool slightly, then slice into 9 squares. Optional: Drizzle with icing before serving.