Preheat oven to 350°F (175°C). Grease and line a 9x9-inch square pan (or 8x10).
Make the crumb topping: In a bowl, mix flour, both sugars, cinnamon, and salt. Cut in the cold butter with a pastry cutter or fork until crumbly. Set aside.
Make the cake: In a medium bowl, whisk flour, baking powder, baking soda, salt, and spices.
In a large bowl, whisk sugars, oil, eggs, pumpkin puree, and vanilla until smooth.
Stir dry ingredients into wet until just combined (don’t overmix).
Spread batter evenly into prepared pan. Sprinkle crumb topping generously over the top.
Bake 35-40 minutes, or until a toothpick inserted in the center comes out clean.
Cool at least 20 minutes before slicing. Drizzle with glaze if desired.