Preheat your oven to 350°F (175°C). Spray a 9x9 or 9x13-inch pan with baking spray and set aside.

To make the crumb topping, whisk together 1 cup flour, brown sugar, cinnamon, nutmeg, and salt. Add cold butter cubes and blend until large crumbs form. Set aside.

In a medium bowl, mix 2 cups flour, baking powder, salt, cinnamon, ginger, nutmeg, and cloves. Set aside.

In a large bowl, whisk pumpkin puree, vegetable oil, and sugar. Add eggs one at a time, whisking after each. Stir in vanilla extract.

Add the dry ingredients in three parts, alternating with the buttermilk in two parts, beginning and ending with dry ingredients. Stir until just combined.

Pour the batter into the prepared pan and spread evenly. Sprinkle the crumb topping over the batter and gently press it in.

Bake for 30–35 minutes (check at 20–25 minutes if using a 9x13 pan), or until a toothpick comes out with a few moist crumbs. Let cool slightly before glazing.

To make the glaze, whisk together powdered sugar, milk, and vanilla until smooth. Drizzle over the warm cake. Slice and serve.