For the sauce:
2 pounds Italian tomatoes or canned whole tomatoes, coarsely chopped
1 tablespoon olive oil
1/2 small yellow onion, finely chopped
1 clove garlic, finely chopped
1 bay leaf
4 basil leaves
2 parsley stems
salt and pepper to taste
For the polenta:
1 1/2 cups polenta
8 ounces Fontina cheese, thinly sliced
5 ounces Gorgonzola cheese
1 tablespoon basil, chopped for garnish
For the sauce:
In a medium saucepan, heat the olive oil over medium heat. Add the onion, garlic, bay leaf, basil and parsley, and cook slowly for 3 to 4 minutes. Add the tomatoes. Bring to a boil, and simmer for 15 minutes. Put sauce in a food processor on pulse to chop tomatoes and make sauce smoother. Return to the sauce to the pan, and simmer until medium-thick. Season to taste with salt and pepper and a pinch of sugar to cut the acidity if necessary. This yields about 1 1/2 cups.
While the sauce is cooking, bring 4 1/2 cups water to a boil and add 1 teaspoon salt. Whisk in the polenta in a stream so that lumps do not form. Lower the heat, and simmer 12 to 15 minutes, while stirring with a wooden spoon. Pour polenta into a loaf pan or a 9-by12-inch baking dish, and set it aside to cool. When cold and firm, turn polenta out on a clean surface, and cut into 3-inch squares or diagonal pieces. Preheat the oven to 400 degrees.
Lightly butter individual gratin dishes, spreading a tablespoon of tomato sauce over bottom of dishes. Arrange the polenta and slices of Fontina in overlapping layers.
Spoon the remaining tomato sauce over the layers. Crumble Gorgonzola over the top, season with pepper, and bake the polenta uncovered until cheese is melted. Garnish with fresh basil.