Lemon Cheze Filling Or Frosting
["4 Tbsp. butter (6 Tbsp. for 3 layers)", "3 egg yolks (4 for 3 layers)", "1 Tbsp. flour (1 1/2 Tbsp. for 3 layers)", "1 c. sugar (1 1/2 c. for 3 layers)", "2 lemons (grated rind and juice)", "1/4 tsp. salt"]
["Mix.", "Cook in double boiler until thick.", "Spread onto two-layer cakes."]
["butter", "egg yolks", "flour", "sugar", "lemons", "salt"]