1 1/2 c. sugar
1 1/2 c. water
1/2 tsp. salt
1/2 c. cornstarch
1/3 c. water
4 egg yolks, slightly beaten
1/2 c. lemon juice
3 tbsp. butter
1 tsp. grated lemon peel

Combine sugar, 1 1/2 cups water and salt in saucepan; heat to boiling. Mix cornstarch and 1/3 cup water to make smooth paste; add to boiling mixture gradually, stirring constantly; cook until thick and clear. Remove from heat.

Combine egg yolks and lemon juice; stir into thickened mixture. Return to heat and cook, stirring constantly, until mixture bubbles again. Remove from heat. Stir in butter and lemon peel. Cover and cool until lukewarm. After piping a dam of frosting on the bottom layer of your cake, pour cooled filling onto cake and add the 2nd layer. This is enough filling for a 3/4 size sheet cake. If your top layer is still warm, it is easy to line both cakes up because the top layer can slide on the warmed dam of icing and the filling.