Preheat oven to 350°F and line muffin tray with paper liners (24 total).
In a large bowl, cream together the butter and sugar until light and fluffy.
Add eggs one at a time, beating well after each addition, then add pumpkin and stir.
In another bowl, combine flour, pie spice, baking powder, cinnamon, salt, baking soda and ginger. Stir to combine.
Slowly add the dry mixture to the batter while beating. Then add the buttermilk and stir until well combined.
Pour the mixture into the muffin cups until 3/4 full. Bake for 20-25 minutes. They're done when a toothpick inserted comes out clean. Remove the cupcakes to a wire cooling rack.
Meanwhile, add the cream cheese and butter to a bowl. Beat until fluffy. Add confectioners' sugar, vanila, and cinnamon and beat until smooth.
Once cupcakes are completely cooled, decorate with the frosting.