To make the mornay sauce, melt the butter in a medium saucepan over medium heat. Add the flour, cook stirring until pale golden color about 2 min. Slowly whisk in cream or milk. Continue to whisk and increase heat to medium-high until the mixture begins to boil. Remove from heat add the cheese, nutmeg and cayenne. Stir well. Adjust seasoning with salt and pepper to taste.

Preheat broiler. For the sandwiches, spread out 10 slices of bread on a rimmed cookie sheet and butter each slice. Broil until golden brown, watch very closely they don't burn, rotate pan halfway through for even cooking. Remove from oven. Turn oven to 450F. Turn bread over and top 5 slices of bread with two slices of ham and one slice of Armstrong Swiss cheese. Top with the other slice of bread, golden side up. Press down slightly. Spread about 2 Tbsp. of the mornay sauce thinning out towards the side but cover the break completely or it will burn. Top with the second slice of Armstrong Swiss and a sprinkling of Parmesan cheeese. Bake sandiwches until the cheese is melted, about 10 min. Run under the broiler to get slightly browned. Serve hot!