Preheat oven to 350°. Grease a 13x9-in. baking pan., In a large bowl, beat pumpkin, sugar, oil and eggs until well blended. In another bowl, whisk flours, baking powder, baking soda, salt and spices; gradually beat into pumpkin mixture. Fold in chocolate chips., Spread into prepared baking pan. Bake 20-25 minutes or until a toothpick inserted in center comes out clean. Cool completely in pan on a wire rack., Meanwhile, in a large bowl, beat butter until creamy. Beat in milk, vanilla and, if desired, cloves. Gradually beat in cocoa and enough confectioners’ sugar to reach a spreading consistency. Spread over top of cake. If desired, sprinkle with additional chocolate chips.