Spray 9×13″ dish with nonstick cooking spray.
Spread pieces of French bread in dish and drizzle with butter. Sprinkle with sausage, Swiss, and Cheddar cheeses. Mix eggs, milk, wine, green onions, mustard and pepper. Beat until foamy. Pour over casserole and refrigerate overnight.
Remove from refrigerator 30 minutes before baking. Preheat oven to 325 degrees. Cover and bake for one hour.
Remove from oven. Spread with sour cream and sprinkle with Parmesan. Bake, uncovered, for an additional 10 minutes, or until lightly browned.