Preheat oven to 425 degrees. In a large skillet, cook sausage, ground beef, onion, and garlic over medium heat until well browned. Stir in marinara sauce.

In a mixing bowl, combine ricotta cheese with egg, and 1/2 tsp salt. To assemble, spread 1 1/2 cups of meat sauce in the bottom of a 9×13 inch baking dish. Arrange chicken breast slices over meat sauce. Spread with one half of the ricotta cheese mixture. Top with a third of mozzarella cheese. Spoon 1 1/2 cups meat sauce over mozzarella, and sprinkle with 1/4 cup Parmesan cheese. Repeat layers, and top with remaining mozzarella and Parmesan cheese. Cover with foil: to prevent sticking, either spray foil with cooking spray or make sure the foil does not touch the cheese.

Bake for 25 minutes. Remove foil, and bake an additional 25 minutes.

Cool for 15 minutes before serving. Makes 12 servings.