Method Heat oven to 350 degrees Fahrenheit. Grease and flour a 9 x 13 inch baking pan
Cream together the butter and sugar in a large bowl until light and fluffy. Add the egg yolks one at a time, beating well with each addition, then stir in the vanilla.
Sieve together the flour and baking powder into a large bowl. Add the flour mixture alternately with the milk; beat well after each addition. In a large glass or metal mixing bowl, beat egg whites and cream of tartar until whites form stiff peaks. Gently fold the egg whites into the cake batter using a rubber spatula. Spread the mixture evenly into the prepared pan
Bake 25 to 30 minutes, or until the center of the cake springs back when gently touched or the cakes start pulling away from the sides of the pan
Allow to cool to room temperature
Stir together the heavy cream, evaporated milk and sweetened condensed milk in a medium bowl and pour over the cooled cake until it wont absorb any more
Cover cake with Whipped cream and refrigerate until serving