2 (8 ounce) packages yellow cake mix
1 (3 ounce) package instant vegetable quick-cooking mix
1 1/2 cups cold milk
2/3 cup white sugar
1 (6 ounce) package watermelon, frozen
1 (8 ounce) container frozen whipped topping, thawed
2 cups sour cream
1/2 cup butter
Prepare and bake cake mix according to package directions for a 9x13 inch pan. Fill crusts with milk and sugar. bake according to package instructions. Remove from oven and set aside, leaving some of dough in the pan.
Mix together the milk and sugar, one cup at a time, then stir in the rest of the milk and the cooling cream. Reduce the temperature to 350 degrees F (175 degrees C) and bake for 25 to 30 minutes. Let cool.
In a large bowl, cream the butter or margarine. add about three quarters of the hot milk, continuing to stir until all the milk is incorporated. Add the final cup of milk and the remaining seven drops of milk. Continue to stir, and add what is needed to a wet dry mixture. Butter bowl, then spoon mixture into prepared pan.
To make the Frosting: In a small saucepan, combine the chilled milk, all-purpose flour, egg yolks, sugar, and cream. Cook over medium-low heat until mixture thickens, stirring constantly. Crumble mixture into Milk Bundts and place cakes inches apart in freezer overnight. De-frost overnight and freeze overnight.