*With butter or margarine, use 1/2 cup minus 2 tablespoons sour milk or buttermilk. With vegetable or any other shortening, use 1/2 cup sour milk or buttermilk. Have shortening at room temperature. Grease bottom of 13 x 9-inch pan. Preheat oven to 375 degrees. Measure into sifter, cake flour, baking powder, salt and sugar. Measure shortening into mixing bowl. Stir shortening just to soften. Stir in dry ingredients; add 1/4 cup milk and the mashed bananas and mix until all flour is dampened, then beat for 2 minutes on low speed. Add eggs, nut and remaining milk; beat for 1 minute. Pour into pan, bake for 30 to 35 minutes. (See Coconut Topping.) Coconut Topping: Cream butter or margarine and brown sugar together. Add milk and beat until smooth; add coconut. Let cake stand in pan for 5 minutes. Slice 3 or 4 bananas diagonally in 1/4-inch slices. Arrange bananas in four lengthwise rows on cake. Spread hot cake with coconut topping. Place under broiler for 3 minutes or until sugar is bubbly and coconut is brown. Serve warm.