Slow Cooker Baked Ziti

Ingredients:
2 lb. bulk Italian pork sausage or ground beef
2 (2 cups) large onions, chopped
2 cups (6 oz.) sliced fresh mushrooms
3 cloves garlic, finely chopped
28 oz. San Martzano diced tomatoes, canned undrained
2 (28 oz.) cans San Martzano tomato puree
6 oz. tomato paste
1 Tablespoon dried basil leaves
1 teaspoon dried oregano leaves
1 Tablespoon sugar
1/2 teaspoon salt
1/2 teaspoon pepper
1/2 teaspoon crushed red pepper flakes
8 oz. mozzarella cheese
1 (16 oz.) box ziti or rigatoni pasta

Directions:
Spray 5 quart slow cooker with cooking spray or use a crock pot liner. In 12 inch skillet, cook sausage, onions, mushrooms, and garlic over medium heat about 10 minutes, stirring occasionally, until sausage is no longer pink; drain. Stir in remaining ingredients, EXCEPT noodles and cheese. Place the uncooked pasta in a colander and run water over the pasta. This will help add moisture to help cook the noodles while in the slow cooker. Put a layer of sauce in the bottom of the slow cooker, layer the noodles, mozzarella cheese, and repeat until all sauce and noodles are gone. Cover. Cook on Low for 8-9 hours or on High for 3-4 hours. Top with remaining mozzarella cheese and turn to High for 30 minutes until cheese is melted.

Optional: 
Sprinkle with Parmesan cheese

Variation:
Can alter recipe to eliminate sausage to make this a vegetarian dish.

Found at http://www.getcrocked.com/2011/10/15/slow-cooker-baked-ziti/