Preheat oven to 375 degrees F. Cook pasta according to package directions. Drain and set aside.
While pasta cooks, mix remaining ingredients in a large bowl. Spray a 1-1/2 qt. casserole dish with cooking spray.
Stir pasta into cheese mixture, then spread into casserole dish. Bake uncovered for 30 minutes in preheated oven, or until hot and bubbly. Stir together before serving to evenly distribute the cheese sauce.