Preheat the griddle. Brush one side of each piece of broiche with butter. Spread the other half with mustard. On four slices of bread, mustard side up, lay a piece of cheese. Place two slices of sausage on top of the cheese. Lay a piece of cheese over the sausage. Place two slices of sausage on top of the cheese. Lay a piece of cheese over the sausage. Top each pile with the remaining bread, mustard side down. In a mixing bowl, whisk the eggs and cream together. Season with salt and pepper. Dip sandwiches in the egg mixture and place on a hot griddle and cook for 2 to 3 minutes on each side, or until golden brown and the cheese has melted.
Cut the sandwiches in half and serve with the fried onions.
Yield: 4 servings