Assemble two sandwiches with 4 slices of ham, and 1 ounce of Swiss cheese. Butter the sandwiches with 1 teaspoon of butter per sandwich. Either broil the sandwiches in a toaster broiler oven or toast in a pan.
To make the sauce heat together 1 tablespoon of butter and 1 tablespoon of flour in a small saucepan. Stir the flour and butter in the saucepan over medium heat. Cook the roux for about 2 minutes. Gradually add the milk in small amounts. Stir the milk in until the sauce is smooth and creamy. Once all of the milk is added add the cheese in small amounts. Add in a pinch of black pepper.
When all of the cheese has been added and it has melted through spoon 2 to 3 tablespoons of sauce over the toasted sandwiches. Sprinkle a bit of cheese over each sandwich and place the sandwich back under a hot broiler until the cheese begins to melt and brown.