STEP 1: Make a Béchamel (White) Sauce by melting the butter WITH the flour in a medium pot over a low to medium heat. Wait until in starts to discolour slightly and smells like “cookies baking in the oven”. Add the milk gradually and stir continuously using a Wisk to ensure there are no lumps. Add Salt, Nutmeg and Parmesan. Stir in, taste and adjust if necessary.
STEP 2: Preheat grill of oven at 200˚C. Pack sliced bread on a oven pan and toast for 2 minutes on each side (check!). Remove from oven, spread Dijon Mustard on half of the slices, top with ham and a slice of Mozzarella. Close the sandwich with the remaining bread slices.
STEP 3: Change oven setting to fan with 200˚C (not grill). Scoop and spread Béchamel on the top of the 8 sandwiches and sprinkle with grated Ementaler. Place in the oven for 8-10 minutes to heat through and grill for a further 2 minutes (check!). Serve hot!