Preheat the oven to 350 degrees F.
In a mixing bowl beat together the butter and sugar until light and creamy.
Add pumpkin puree, and beat for 1 minute.
Add cinnamon, nutmeg, salt, vanilla, and eggs, and mix well.
Add the baking powder and flour, a little at a time, and mix just until incorporated.
Spread the batter into a greased 9x13 pan.
In a small bowl whisk together the topping ingredients and sprinkle evenly on top of the batter.
Bake for 20 minutes or until a toothpick inserted into the center of the pan comes out with fudgy crumbs but NOT raw batter. Do not overbake.
Cool on a cooling rack for 15 minutes before slicing.
