Sweet Potato Corn Bread

1 large sweet potato (to make 2 cups pulp)
1/4 pound butter
4 eggs, beaten
1/2 cup brown sugar
1/2 teaspoon baking soda
1 teaspoon salt
1 teaspoon cinnamon
1 cup yogurt
2 cups finely ground white cornmeal
1/2 cup sultana raisins (optional)
1/2 cup pecans (optional)

Bake or boil the sweet potato in its skin; when cool enough to handle, peel it and puree the pulp.

Mix together butter and pureed pulp.

Beat eggs with sugar, baking soda, cinnamon and salt, and add to the puree. Beat in yogurt, cornmeal and optional raisins and nut. Pour into a buttered 9-inch square baking pan and bake at 350 degrees F until browned, 45 to 60 minutes.