2 Tb. corn starch 1/3 c. sugar 1/2 c. boiling water 1 Tb. butter 1 lemon 1 egg
Mix the corn starch and sugar, and add to this the boiling water. Put to cook in a double boiler, add the butter, the grated rind of the lemon, and cook for 15 or 20 minutes. Beat the egg slowly, add to the mixture, and cook for 5 minutes more. Remove from the heat and add the juice of the lemon. Cool and spread between layers of cake.