6 Tablespoons butter
4 Tablespoons milk
2 teaspoons cream of tartar
1 teaspoon soda (or baking powder)
2/3 teaspoon salt
Have the bowl slightly warm, measure butter into it and beat butter until creamy, add sugar slowly, the yolks well beaten, flavoring. Mix and sift the flour and baking bowder and add to the mixture, alternating with the milk; fold in the egg whites beaten very stiff. Do not stir after the whites are added.
Bake in a greased, flour-dusted pan at 350°F until the cake comes away from the edge of the pan.
Filling for cake
1 1/2 cups sugar
1/2 cup butter
Rind of 3 lemons grated, and the juice
Beat the butter, sugar and eggs together. Set a dish of boiling water until heated; then add the lemon and stir until thick. Spread between layers of cake.