Preheat oven to 350 degrees. Butter and flour a 9- inch spring form pan. In a bowl combine flour, baking powder, cinnamon, and cloves. In another bowl, beat egg whites until foamy, add in 3 tablespoons sugar; beat until stiff peaks form. In a large bowl, beat egg yolks with the remaining sugar until pale, about 1 minute. Add pumpkin and vanilla and beat until well blended. Stir in flour mixture. Fold in egg whites and pecans. Pour into the prepared pan. Bake for 40 - 50 minutes, let cool 10 minutes, and remove from pan. Serve each slice with whipped cream, mint, candied pecans, or powdered sugar