Banana Cake with Penuche Frosting

Yield: 16 servings. Sift the cake flour, baking powder, baking soda, and salt, blending well and set aside. Place the vinegar in a measuring cup. Add enough milk to make 2/3 cup and set aside. Cream the shortening and sugar together, in a large mixing bowl, until light and fluffy, using an electric mixer set on medium speed. Add the eggs, one at a time, beating well after each addition. Add the dry ingredients alternately with the milk mixture and bananas to the cream mixture, blending well after each addition, using low speed on the mixer. Stir in the walnuts and pour the batter into a greased 13 X 9 X 2-inch baking pan. Bake in a preheated 350F oven for about 45 minutes or until a cake tester or wooden pick inserted in the center comes out clean. Cool, in the pan, on a wire rack until cold to the touch, then frost. Heat the butter in a 2-quart saucepan, over medium heat, until bubbling but not browned. Stir in the brown sugar. Cook, stirring constantly, until the mixture comes to a boil. Reduce the heat to low and cook, stirring constantly, another 2 minutes. Stir in the milk. Increase the heat to medium and cook until the mixture returns to a boil. Remove from the heat and cool to lukewarm. When the mixture is lukewarm, stir in the Confectioners' sugar and beat with a wooden spoon until well blended and thick enough to spread. If necessary, place the pan in a bowl of ice water and beat with a wooden spoon until the frosting reaches a spreading consistency. If the frosting becomes too stiff, warm over low heat.