In a large skillet brown your Italian sausage, ground beef, onion and minced garlic for a few minutes over medium heat until the meat is cooked through. Drain out the extra grease.
Pour in your Tomato Pasta Sauce and stir together. Allow to simmer for a bout 10 minutes.
In a large bowl, combine 3 cups of the mozzarella cheese, ricotta, Parmesan and egg. Stir it all together, and set it aside.
Spread 1/4 of the meat mixture onto the bottom of a 6 quart slow cooker.
Arrange 1/3 of your noodles on top of your meat mixture. You may need to break some of the noodles to get them to fit.
Spread 1/3 of your cheese over the noodles.
Repeat these layers twice with more meat, noodles, cheese - meat, noodles, cheese.
Top with remaining meat sauce.
Sprinkle remaining 1 cup of mozzarella cheese over the sauce.
Cover and cook on low for 4-6 hours, until the noodles are tender and cheese is melted and golden.