Cook pasta according to directions until the pasta is al dente edible but still a little firm. Drain the pasta in a colander. Toss with a little olive oil so the pasta does not stick together while you make the sauce.
Brown well sausage and ground meat. Add the onions and stir well to combine. Saute everything until the onions are translucent and beginning to brown, about 4-5 minutes. Then add the tomato sauce and stir well. Bring to a simmer.
Preheat the oven to 350°F. Spread pasta on the bottom of a 9×13-inch casserole pan, then layer half of the mozzarella cheese. Layer on the pasta and then the rest of the mozzarella cheese. Last, layer the parmesan cheese.
Cover with foil and bake for 30 minutes. I have found if I cover this it keeps the cheese from burning and drying out the casserole since the meat sauce is so thick.