Preheat your oven to 430°F – 220°C

In a small saucepan, melt the butter, add the flour and stir with wooden spoon for 60 seconds over low heat. Gradually stir in warm milk in several stages as you mix. Once thick, keep cooking for a couple minutes longer to cook off the flour. It should become smooth. Season with a touch of salt and nice amount of pepper and grated nutmeg. Set aside.

Slice the bread into thick slices. Toast the bread evenly in toaster or under the broiler. Toast both sides.

Spread some Dijon mustard onto two slices, one side only. Place the bread slices, on a foil lined baking tray.

Divide and evenly spread all the béchamel onto the four slices including the mustard ones.

Place two or three thin slices of ham, enough to cover two of the toasts, over the bechamel.

Add the slices of cheese on top of the ham and over the bechamel. Enough to cover and even overhang.

Place the slices without the ham on top over the others. Bake in oven for 10 minutes at 430°F – 220°C.
You can also turn on the broiler or top grill to help brown for the last 2 minutes. Serve straight out of oven, ideally with a well-seasoned green salad.