In a large bowl, cream butter and sugar until light and fluffy. Beat in eggs, pumpkin and vanilla. Combine the flour, cinnamon, baking powder, baking soda, nutmeg, salt, ginger and cloves; add to pumpkin mixture alternately with buttermilk beating well after each addition.
Pour into three greased and floured 9-in. round baking pans. Bake at 325° for 20-25 minutes or until a toothpick inserted near the center comes out clean. Cool for 5 minutes before removing from pans to wire racks to cool completely.
In a large bowl, beat cream cheese and butter until smooth. Add confectioners' sugar and enough maple flavoring to achieve spreading consistency. Place one cake layer on a serving plate; spread with 1 cup frosting. Repeat with remaining layers and frosting. Garnish with walnuts. Store in the refrigerator. Yield: 10-12 servings.