Preheat oven to 350 degrees.

Bring a pot of water to a boil and cook the rotini pasta according to package directions.

In the meantime, add the sausage and onion to the skillet and cook until fully browned. Drain.

When pasta in cooked and drained, add it back into the pot it was cooked in along with the cooked sausage and onion, followed but the cottage cheese and marinara sauce.

Add to a 9 x 13 inch baking dish. Top with shredded mozzarella cheese.

Bake at 350 degrees for 15 minutes or until cheese is bubbly. Serves 6.