1Spread one side of 4 bread slices with mustard. Top remaining 4 slices with ham. Combine mozzarella and Parmesan cheeses and mix together; sprinkle mixture evenly over ham and close sandwiches, mustard side down.
2In a shallow dish or bowl combine the eggs, milk and nutmeg and mix well. Melt butter in a large skillet or on a griddle over medium heat. Dip each sandwich in egg mixture, turning to coat. Let excess egg mixture drip into dish or bowl, and place sandwiches in hot skillet. Cook until golden brown and cheese is melted.