In a large bowl, cream 3/4 cup of butter and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition. Add pumpkin.
Combine dry ingredients (flour, pumpkin pie spice, baking powder, cinnamon, salt, baking soda and ginger); add to the sugar/butter mixture alternatively with the buttermilk, beating well after each addition.
Fill paper-lined muffin cups 3/4 full. Bake at 350º for 20-25 minutes or until a toothpick inserted into the center comes out clean. Cool for ten minutes before removing from pans to wire racks to cool completely.
FOR FROSTING: In a large bowl, beat cream cheese and 1/2 cup of butter until fluffy. Add the powdered sugar, vanilla and cinnamon. Beat until smooth. Frost cupcakes. Refrigerate leftovers. Yield: 2 dozen