Prep: 1. Preheat oven to 375. 2. Boil water for pasta. 3. Remove casings of sausages. 4. Chop: onion, garlic, and mozzarella. 5. Grate parmesan. Make: 1. Cook ziti according to package instructions. 2. In a large saucepan, sauté sausage, onion and garlic until sausage is cooked through, about 10 minutes. 3. Add tomatoes with juices to pan. Simmer until sauce thickens slightly, stirring occasionally, about 10 min. 4. Stir in pesto. Season sauce with salt and pepper. 5. Lightly oil a 13 x 9-inch glass baking dish. Combine pasta, spinach, mozzarella and 1/3 cup parmesan cheese in large bowl. Stir in hot tomato sauce. 6. Transfer mixture to prepared baking dish. 7. Sprinkle remaining 2/3 cup parmesan cheese over. 8. Bake until sauce bubbles and cheeses melt, about 30 min.