In a Dutch oven, cook sausage, ground beef, and onion, over medium heat until well browned.
Add sliced mushrooms and cook until softened.
Drain off excess fat and return to heat. Stir in garlic and cook until fragrant, about 1-2 minutes.
Stir in crushed tomatoes, tomato paste, tomato sauce, and water.
Add sugar, basil, fennel seeds, Italian seasoning, salt, pepper, and chopped parsley.
Simmer on the stovetop, covered, for about 1 ½ hours, stirring occasionally.
In a mixing bowl combine cooked rigatoni noodles, half the shredded Mozzarella cheese and enough sauce to coat the noodles and cheese.
Transfer pasta into a 13x9 inch oven safe casserole dish.
Top pasta with remaining Mozzarella cheese.
Sprinkle with shredded parmesan cheese.
Cover casserole with foil.
Bake for 45 minutes until heated all the way through.
Remove foil and set oven to broil. Cook until cheese is lightly browned and bubbly.
Remove from oven and allow casserole to sit for 10 minutes before serving.