Preheat oven to 350ºF. In a large mixing bowl, combine the sugar, ginger, flour, baking soda, baking powder, salt, and cinnamon. Cut in the butter about 1 tablespoon at a time using a pastry knife or your fingers.
In a separate bowl, combine the pumpkin, egg, vanilla, and sour cream. Add the pumpkin mixture to the flour and stir until combined.
Place one tablespoon of dough on an un-greased cookie sheet about an inch apart. Bake for 20-25 minutes or until a toothpick comes out clean. Serve warm.