Preheat the oven to 400 degrees.  Grease a 9-inch square baking pan and set aside.

Scrub the potatoes, then poke them with holes and wrap in foil.  Bake the potatoes at 400 degrees for about an hour or until tender.  If you are pressed for time, you can peel the potatoes, cut into cubes and boil for 15-20 minutes or until tender.  Drain and cool.

In a small bowl stir together the cornmeal, flour, sugar, baking power, salt, baking soda, cinnamon and allspice.  Stir well.

Add the sweet potatoes to a food processor and pulse until blended.

Scrape into a bowl and add buttermilk, eggs, and melted butter.  Mix well.

Slowly add the dry ingredients.  Stir until combined, careful not to over mix.  The batter should be slightly lumpy.

Pour the mixture to the pan and bake about 35-40 minutes or until the top is golden brown.  To make sure it’s done, stick a toothpick in the center.  If it’s ready, the toothpick will come out clean.  Cool slightly, cut into squares and serve with butter.