Preheat oven to 350 degrees. In a large bowl beat the butter with an electric mixer on medium speed for 30 seconds. Add granulated sugar, baking powder, baking soda, salt, the cinnamon, and the nutmeg. Beat until combined. Beat in the eggs and the vanilla until combined. Beat in pumpkin. Beat in as much of the flour as you can with the mixer. Stir in remaining flour with a wooden spoon.

Drop dough by heaping teaspoons 2 inches apart on ungreased cookie sheets. Bake for 10 to 12 minutes or until tops are set. Transfer to wire racks to cool.

For frosting, in a small saucepan heat the frosting butter and brown sugar until melted and smooth. Transfer to a medium bowl. Stir in the milk and frosting vanilla. Beat in powdered sugar until smooth. Spread frosting on cookies. Sprinkle with additional cinnamon if desired.