Tennessee Skillet Sweet Taters

3 cups cooked and mashed sweet potatoes
1 1/2 cups granulated sugar
1/4 cup self-rising flour
2 eggs
1/2 cup (1 stick) butter or margarine
1 teaspoon vanilla extract
1 teaspoon nutmeg or allspice

Melt butter or margarine. Mix all ingredients together. Bake in a cast iron skillet or baking pan at 350 degrees F for 40 to 45 minutes. Let cool and serve.