Stir together flour, baking powder, baking soda, salt, and spices. Beat butter or margarine for 30 seconds. Add brown sugar and beat until fluffy. Add egg and vanilla, beating well. Add dry ingredients and sour cream alternately, beating after each addition. Stir in nuts. Drop by teaspoons onto a greased cookie sheet. Bake at 375 for 8 to 10 minutes or until lightly browned. Remove from cookie sheet immediately and cool on wire racks. Frost cooled cookies with Browned Butter Frosting.