Preheat oven to 350°.
In a medium bowl, combine flour, baking powder, and pumpkin pie spice. Set aside.
In a separate mixing bowl, cream butter and brown sugar.
Mix in pumpkin puree, milk, and egg.
Add dry ingredients and mix just until blended.
Spoon batter into a greased 8x8 inch baking pan.
Prepare streusel by mixing ingredients together with a fork or pastry blender until they resemble coarse crumbs.
Sprinkle streusel topping evenly over batter
Bake at 350° for 50-60 minutes, until top is golden brown and toothpick inserted in center comes out clean.