Preheat oven to 350 degrees. Cream butter and sugar until fluffy. Add pumpkin, egg and vanilla and mix well. Combine flour, baking powder, baking soda, salt, cinnamon and nutmeg. Stir into butter mixture until well blended. Add nuts and raisins. Drop by teaspoonful onto parchment covered baking sheet, about 2 inches apart. Bake about 15 minutes, or until golden. Cool.
Icing: Cream confectioners' sugar and butter. Add remaining ingredients and beat until smooth. (If icing is too thin, add more confectioners' sugar; if too thick, add more cream, orange juice or rum.) Drizzle over cookies.