Cream the butter and sugar together until light and creamy. Beat in the egg until it's fully incorporated.
Mix in the pumpkin puree and vanilla.
Put all your dry ingredients in a bowl and whisk them together, then slowly add the dry to the wet. Mix, and when done, drop by large tablespoons onto a well greased cookie sheet.
Bake in a 350 degree oven until they are lightly browned, around 15 minutes. Cool.
Prepare either icing and frost the cookies. Store in an airtight container for up to three days.
Notes
Calories are calculated with the icing glaze, not the buttercream icing.