Preheat the oven to 350°F. Grease a large baking dish.
STEP 2
Bring a large pot of lightly salted water to a boil. Cook rigatoni until tender, about 12 minutes. Drain and set aside.
STEP 3
Cook sausage and onion in a skillet until sausage is no longer pink, 5 to 7 minutes.
STEP 4
In a large bowl, combine sauce, cottage cheese, 1 cup mozzarella, Parmesan, eggs, parsley, Italian seasoning, basil, salt, and pepper. Add sausage and pasta; mix well. Transfer to baking dish; cover.
STEP 5
Bake for 45 minutes. Top with remaining mozzarella; continue baking until cheese melts, about 15 minutes.