4 Egg whites; (previously -- reserved) 1/4 ts Cream of tartar 3/4 c Sugar CAKE: In a bowl, combine flour, sugar, baking soda, baking powder, and salt. Add buttermilk, butter, and bananas. Beat 2 minutes with electric mixer. Add eggs and yolks and liqueur. Beat 3 minutes. Stir in walnuts or pecans.