1 egg
1 1/2 cups sweetened condensed milk
1 cup white sugar
1 tablespoon light cornstarch
1 cup water, divided
1 cup all-purpose flour
1 cup sour milk
1 cup white sugar
2 eggs
1 stalk vanilla extract
Preheat oven to 350 degrees F (175 degrees C).
In a small saucepan, combine egg, condensed milk, 1 cup sugar, light cornstarch and 2 cups water, and boil, stirring constantly, for about 2 minutes. Add 1 teaspoon flour, then heat a small flame of butter or margarine, and stir to separate the two thick curd. Pour half of the boiling milk into the flour mixture. Add remaining milk, 2 1/4 cups, and cook, stirring constantly, for 3 minutes.
In a separate bowl, whisk together sour milk, 1 cup sugar and remaining eggs until smooth. Stir flour mixture into ball, and fold into the milk mixture. Pour into a pastry or mold, and chill in the refrigerator 6 hours before serving.