Brush both sides of each slice of bread with some of the melted butter and transfer to a preheated oven at 200 C / Gas 6 for 5 minutes. Take them out, turn them and return them to the oven for another 5 minutes.
Once they have cooled enough to handle, rub the cut surface of the garlic clove on one side of two of the slices.
Heat the remaining melted butter in a pan and whisk in the flour. Allow to cook for a few minutes to cook out the raw flour taste.
Whisk in the milk in a few batches followed by the nutmeg and half your cheese. Whisk until melted, incorporated and thickened. Then take it off the heat to assemble the sandwiches.
Spread the Dijon on the slices of toast that weren't rubbed with garlic and sprinkle over a little of the remaining cheese.
Add 2 slices of parma ham to each sandwich letting them fall loosely on the cheese.
Add another layer of cheese and top with the garlic toasts and press them down to compress the sandwiches a little.
Pour the white sauce generously over each sandwich and finish with the remaining grated cheese.
Place them under a hot grill or in a hot oven and allow them to turn brown and molten.
Snip the fresh chives over to garnish and serve with a green salad.
Such a tasty recipe that serves two, but if cooking for a crowd it can be scaled up with no extra work.