Preheat oven to 350°
Mix the flour, baking powder, pumpkin pie spice, baking soda in a small mixing bowl
In a large mixing bowl, add the eggs, pumpkin, buttermilk, brown sugar, sugar, canola oil and vanilla mix until well blended
Add the flour mixture and mix just until combined
Add the batter into a 9x9 pan or a round cake pan that is sprayed with cooking spray
Sprinkle the topping evenly over the top of the cake
Bake at 350 degrees for 40 to 45 minutes or until knife or toothpick comes out clean when inserted into the center