In a large skillet, cook sausage and onion over medium heat until meat is no longer pink; drain.

Transfer to a greased 13-in. x 9-in. baking dish. Sprinkle with cheese.

Combine eggs and soup; pour over cheese.

Bake, uncovered, at 400° for 30-35 minutes or until a knife inserted near the center comes out clean. Let stand for 5 minutes before cutting. Serves 8.