1 (18.25 oz.) yellow cake mix
3/4 c. sugar
3 tbsp. cornstarch
1/4 tsp. salt
3/4 c. water
1 tsp. grated lemon rind
1 tbsp. butter
1/3 c. fresh lemon juice
2 drops of yellow food coloring
1 (6 oz.) container of vanilla frosting

Prepare cake mix according to package directions for 2 (8 inch) cake layers. Cool for 15 minutes. Mix sugar, cornstarch and salt in saucepan, stir in water gradually. Cook stirring constantly until mixture thickens and boils. Boil and stir 1 minute; remove from heat. Stir in butter and lemon peel until butter is melted. Gradually stir in lemon juice and food coloring. Press plastic wrap onto filling. Refrigerate until set at least two hours. Fill layers and top with filling. Frost sides with vanilla frosting. Yield 1 cake.