Yellow Cake with Caramel Icing

CAKE:
3 cups flour
1 tablespoon double-acting baking powder
2 sticks unsalted butter, softened
2 cups sugar
4 large eggs
1 cup milk
1 teaspoon vanilla

ICING:
10 tablespoons unsalted butter
1 1/4 cups firmly packed brown sugar
1/4 cup + 2 tbl. milk
1 1/4 teaspoons vanilla
3 cups sifted powdered sugar

Make the cake layers: Preheat the oven to 350�F. Line 2 buttered 9-inch round cake pans with rounds of wax paper, butter the paper, and dust the pans with flour, knocking out the excess. Onto a sheet of wax paper sift twice the flour and the baking powder. In a bowl with an electric mixer cream the butter with the sugar until the mixture is light and fluffy and beat in the egg yolks, 1 at a time, beating well after each addition. Add the flour mixture to the butter mixture in batches alternately with the milk, beginning and ending with the flour mixture, and beat in the vanilla.

In another bowl beat the egg whites with a pinch of salt until they just hold stiff peaks, stir one third of them into the batter to lighten it, and fold in the remaining whites gently but thoroughly. Divide the batter between the prepared pans, smoothing the tops, and bake the layers in the middle of the oven for 30 to 40 minutes, or until a tester comes out clean. Let the cake layers cool in the pans on racks for 10 minutes and turn them out onto the racks. Discard the wax paper and let the layers cool completely.

Make the icing: In a small saucepan melt the butter over moderate heat, add the brown sugar, and bring the mixture to a boil. Add the milk in a stream, whisking, and bring the mixture to a boil. Remove the pan from the heat and let the mixture cool completely. In the bowl of an electric mixer beat together the brown sugar mixture and the vanilla. Add the confectioners' sugar in batches, beating, and beat the icing until it is light and fluffy. Assemble the cake: On a cake plate arrange 1 of the cake layers, spread the layer with one third of the icing, and top the icing with the remaining layer. Spread the top and side of the cake with the remaining icing.