Steam the chicory. Let it cool and squeeze it well to remove excess moisture.
Melt the butter in a large stew over medium heat until it foams. Then add the flour in one go and let it fry.
Add half of the milk, beat powerfully to avoid lumps until you have a smooth mass. Then add the remaining milk and keep beating until the mixture boils.
Stir half of the grated cheese into the sauce and season with pepper, salt and nutmeg to taste.
Cook the macaroni according to the cooking instructions on the package.
Cut the ham into strips and add to the sauce together with the pre -cooked macaroni.
Cut the steamed chicory into large pieces and stir half into the macaroni mixture. Then pour this into a baking dish.
Spread the remaining chicory pieces on the macaroni mixture and sprinkle with the remaining cheese.
Gratine the dish for about 30 minutes in a preheated oven at 190 ° C until the top is golden brown. Serve the gratin immediately.