Cook pasta according to package directions. Drain.
If using Italian sausage, place in frying pan and cook, breaking up the meat as you cook, over medium heat, until cooked through and no longer pink. Drain well on paper towels.
Toss pasta with jar of pasta sauce. Pour into a 9x13-inch casserole dish. Top with cheese, Italian sausage, and any other pizza toppings (i.e. pepperoni, olives, bell pepper, etc).
Bake until cheese is melted, about 10-15 minutes. Serve hot.