Lemon Cream Filling - cooking recipe

Ingredients

1 egg yolk, beaten
1/2 cup sugar
2 tablespoons cornstarch
1/4 cup lemon juice
1/8 teaspoon grated lemon, rind of
1/2 teaspoon butter
1/2 cup water

Preparation

Combine yolk, sugar, corn starch, 1/2 cup water, lemon juice, lemon peel and cook in double boiler for 15 minutes.
Add butter.
Cool.