Preheat oven to 375°F. Spray a 16- x 9-inch baking dish with nonstick spray.
Whisk together cream, eggs, salt, pepper, and nutmeg in a large bowl. Toss cheeses together in a small bowl until combined; remove 1 cup cheese and set aside. Stir remaining cheeses into cream mixture.
Cook macaroni until just tender; drain and add cream mixture, stirring immediately. Pour mixture into prepared baking dish. Cover with foil.
Bake 30 minutes. Remove foil and sprinkle reserved cheese over top of noodles. Bake 15 minutes longer.
Cool 10 minutes before cutting into squares. Serve warm.
To add protein to this dish, add 2 cups of diced ham to the macaroni mixture before baking.