1Heat oven to 375°F. Spray 13x9-inch (3-quart) glass baking dish with cooking spray. Place butter in dish; place in oven until melted, about 10 minutes.
2In medium bowl, mix Bisquick mix, 1 cup of the milk and 2 of the eggs with whisk until tiny lumps remain. Pour over butter in baking dish. Layer with Swiss cheese, ham, bacon and Cheddar cheese. In large bowl, mix remaining 1 cup milk, remaining 6 eggs, the salt, mustard and nutmeg. Pour over casserole.
3Bake uncovered 35 to 40 minutes or until golden brown. Let stand 10 minutes before serving.