Ingredients:

Preparation:

Combine cheeses, mayonnaise, mustard, and chopped onion. Spread mixture on one side of 4 of the bread slices to within 1/4-inch of edges. Top with remaining bread slices. Spread softened butter on the outer sides of the sandwiches. Cook over medium heat in a hot skillet or griddle until golden brown, turning once.

Nutritional Information:

590 Calories (kcal); 46g Total Fat; (69% calories from fat); 20g Protein; 26g Carbohydrate; 94mg Cholesterol; 787mg Sodium