Delicate White Cake with Lemon Filling

White Cake:
1/2 cup shortening
1 1/2 cups granulated sugar
2 1/4 cups sifted cake flour
4 teaspoons baking powder
1/2 teaspoon salt
1/2 cup milk
1/2 cup water
1/4 teaspoon vanilla extract
5 egg whites, stiffly beaten

Cream shortening; add sugar gradually and cream thoroughly. Sift flour, baking powder and salt together and add to sugar mixture alternately with the milk and water mixed. Add vanilla extract and fold in egg whites. Pour into 2 well-greased and floured 8-inch cake pans. Bake at 350 degrees F for 30 to 35 minutes. Cool. Remove from pans.

Lemon Filling:
5 egg yolks
1 cup granulated sugar
1/2 cup lemon juice
2 tablespoons grated lemon rind
Confectioners' sugar

Beat egg yolks and add remaining ingredients. Place mixture in top of double boiler and cook over hot water until thick. Let filling cool, then spread between cake layers. Dust cake with confectioners' sugar.