Pasta Rustica with Chicken Sausage and Three Cheeses

INGREDIENTS

• 2 Tbs. olive oil
• 1 yellow onion, chopped
• 2 garlic cloves, minced
• 3/4 lb. chicken or turkey sausage, casings
• removed
• 1 tsp. dried basil
• 1 tsp. dried oregano
• 1/4 tsp. hot red pepper flakes
• 1 can (28 oz.) tomatoes in puree, tomatoes
• coarsely chopped and puree reserved
• Salt, to taste
• 1 lb. penne pasta
• 1 1/4 cups ricotta cheese
• 2 cups shredded fontina or mozzarella cheese
• 1/2 cup grated Parmigiano-Reggiano cheese