Ingredients:
1 1/2 cups white sugar
2 eggs
4 egg yolks
1 cup milk
1/2 cup butter
2 1/2 cups all-purpose flour
1 tablespoon baking powder
1 teaspoon vanilla extract
Frosting:
1 3/4 cups white sugar
1/2 cup water
4 egg whites, room temperature
1 teaspoon vanilla extract
1/2 teaspoon cream of tartar
2 cups sweetened flaked coconut, or as needed