Stir together flour, baking powder, baking soda, salt, and spices. In a mixer bowl, beat butter or margarine for 30 seconds. Add sugar and beat until fluffy. Add eggs and vanilla. Beat well. Add dry ingredients and banana alternately, beating after each addition. Stir in walnuts. Drop by teaspoons onto well-greased cookie sheet. Bake at 375 for 10 to 12 minutes. Remove from cookie sheet immediately and cool on wire rack. Frost cooled cookies with Banana Butter Frosting.