Instructions: Step 1: To prepare the sandwiches, in a 10-inch nonstick skillet, melt butter over moderate heat. Cook mushrooms, onions, and pepper in butter until vegetables are tender. Remove from skillet.

Step 2: For each sandwich, layer a slice of bread, a slice of American cheese, some of the mushroom-onion mixture, a half-slice of mozzarella cheese, and another slice of bread.

Step 3: To prepare the egg coating, in a shallow bowl, whisk together the egg, egg white, and milk. Dip sandwiches in coating to coat on both sides. Wipe out skillet. Coat skillet with cooking spray. In the skillet, cook sandwiches, 2 at a time, over moderate heat until bread is golden and cheese begins to melt, turning once.

NOTES : Originally, these luscious, hot sandwiches were coated in egg like French toast and then deep fried. Todays lighter version uses egg whites and is pan fried to give the same golden brown crust and creamy center with less fat.

Preparation Time: 10 minutes.

Cooking Time: 13 minutes.

Makes 4 main-dish servings.

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