Cake Batter: In a mixing bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and pumpkin spice. In a separate bowl, mix together the sugar, pumpkin puree, oil, eggs, and vanilla extract. Add the flour mixture to the pumpkin mixture and stir until just moistened.
Crumb Topping: Whisk together the flour, sugar, brown sugar, and cinnamon. Add the cubed butter and mix with a fork or a pastry blender until crumbs form.
Grease and flour a 9 inch square cake pan. Pour the cake batter in the pan and sprinkle evenly with the crumb topping.
Bake the cake at 350 degrees for 30-35 minutes, until a toothpick inserted comes out clean. Allow the cake to cool completely.
Glaze: Whisk together the powdered sugar and milk Drizzle the glaze over the cooled cake.