Trudy Reynolds of Indigo in Malibu make her white cake from scratch. The recipe required more than two dozen egg whites, too many for most busy moms, especially when the cake is to be consumed by kids in a hurry. This recipe, then, is a compromise version of her cake. If you prefer, you can make the 2 (13x9-inch) pans of white cake yourself as well. The brownies are still made from scratch; the recipe is simple. But if that's still too much pre-party work, you could also make the brownies from a mix and even skip the frosting recipes by decorate the cake with packaged white and dark chocolate frosting. This recipe will leave you with half of a white cake to do with as you will.      2 ( 18.25-ounce) boxes white cake mix      White Icing      Brownies      Dark Chocolate Frosting      Bake white cakes according to package directions in 2 (13x9-inch) pans. Frost tops of both white cakes with white icing and the brownies with the dark chocolate icing. Ice sides of white cake with remaining dark icing.      Cut brownie and remaining white cake into 5 cm squares. Arrange frosted brownie and white cake squares on top of cake in chessboard pattern. Using pastry bag, pipe remaining white icing into cracks between squares.      21 servings. Each serving:      663 calories; 461 mg sodium; 80 mg cholesterol; 29 grams fat; 103 grams carbohydrates; 5 grams protein;

1.22 grams fiber.      WHITE ICING       half cup (1 stick) butter, room temperature      4 cups powdered sugar       half teaspoon salt      2 teaspoons vanilla extract       quarter to one third cup whipping cream      Cream together butter and sugar until light and fluffy. Beat in salt and vanilla extract. With mixer running, add whipping cream just to stiff, spreadable consistency.      BROWNIES       0.75 cup ( 1.5 sticks) butter       quarter pound unsweetened baking chocolate      2 cups sugar      3 eggs      2 teaspoons vanilla extract      1 cup flour      Melt butter and chocolate together. Beat in sugar. Beat in eggs and vanilla extract. Fold in flour. Pour into greased and floured 8x8-inch baking pan and bake at 350 degrees until brownies appear dry on top and are slightly firm, 30 to 35 minutes.      DARK CHOCOLATE ICING      3 tablespoons butter      9 ounces semisweet chocolate pieces       0.75 cups whipping cream      2 teaspoons vanilla extract      3 cups powdered sugar      Melt butter and chocolate in microwave about 4 minutes. Add whipping cream, vanilla and sugar and beat until smooth.