1 large sweet potato
2 1/2 cups milk
2 cups half & half
1 tablespoon salt
3 teaspoons sugar
1 cup cornmeal
1/2 cup flour
8 tablespoons butter, cut into pieces
6 eggs, separated
1/4 cup cream
Bake sweet potato in center of 325˚F oven until tender, about 1 hour. Peel and purée the baked sweet potato until it is smooth. Set aside.
Butter a 9 X 13 shallow baking dish. Heat milk, half & half, salt and sugar in a heavy saucepan over medium heat. When small bubbles appear around the edge, slowly whisk in cornmeal and flour, stirring constantly. Continue to stir as mixture cooks and thickens. When smooth and creamy, remove from heat and stir in butter until completely melted and combined.
In a medium bowl, beat yolks and cream together until lightened in color. Gradually add to cornmeal mixture. Add 3/4 cup sweet potato puree. Add salt to taste, if desired. Recipe can be made ahead to this point.
Preheat oven to 350˚F. Beat egg whites and fold into cornmeal mixture. Spread into prepared dish. Bake until puffy, golden brown and just set, about 30 to 35 minutes.