1. Preheat oven to 400°. Cook chopped pancetta in a large sauté pan over medium-high heat 7 minutes or until crisp (most of fat is rendered). Reduce heat to medium. Add onion, celery, and garlic, and sauté 8 minutes or until vegetables begin to soften; transfer to a large mixing bowl, and let cool 10 minutes. Stir in remaining ingredients.
2. Spoon mixture into a lightly greased 9-inch square baking pan. Bake, covered with foil, at 400° for 20 minutes. Uncover, and bake 25 to 30 minutes or until browned. Let stand 10 minutes before serving.
*If pancetta (Italian bacon that's cured with salt and spices but not smoked) is unavailable, substitute uncured bacon or ham. You can also use olive oil or butter, but they slightly alter the flavor.
**Fantastic fresh wild mushrooms have become much easier to get. But if they're unavailable, try dried mushrooms for great flavor. The liquid they produce also tastes terrific and can be used for broth, soups, and sauces. (If using dried mushrooms, rehydrate in 2 1/2 cups warm water; strain and reserve liquid to use as broth. Chop after rehydrating.)