Baked Vegetarian Ziti

Name: Baked Vegetarian Ziti
Ingredients: 1 white or yellow onion (peeled and cut into chunks); 3 garlic cloves; 8 ounces mushrooms (cleaned and stems removed); 2 carrots (peeled and cut into chunks); 2 celery stalks (cut into chunks); 2 tablespoons olive oil; 1/2 teaspoon salt; 28- ounce can tomato puree; 16 ounces ziti or penne pasta (cooked); 16 ounces cottage cheese or ricotta cheese; 1/8 teaspoon nutmeg (just a pinch!); 1/4 teaspoon freshly ground pepper; 1 1/2 cups mozzarella cheese