For the Jerusalem Artichoke Gratin, boil Jerusalem artichoke with peel in hot water until tender (30 to 40 minutes depending on size). Peel while still warm and cut into 1 cm thick slices. Layer in a greased gratin dish.
Mix milk with horseradish, salt, whipping cream and pepper and pour over Jerusalem artichoke slices. Drizzle with maple syrup. Spread butter in flakes on top and sprinkle with breadcrumbs.
Bake in the preheated oven at 200 degrees for about 25 minutes. Arrange the Jerusalem artichoke gratin and serve.