In a large skillet, saute apple slices in 1 teaspoon butter until tender. Meanwhile, in a small skillet, cook and stir the walnuts and honey over medium heat for 2-3 minutes or until lightly toasted.
In a small bowl, beat the cream cheese, confectioners' sugar and cinnamon until smooth. Stir in walnut mixture. Spread over 2 slices of bread; layer with Muenster cheese, apple slices and remaining bread. Spread remaining butter over the outsides of each sandwich.
In a large skillet coated with cooking spray, toast sandwiches for 1-2 minutes on each side or until golden brown and cheese is melted.