Preheat the oven to 180 °. Peel and wash the potatoes and cook them in plenty of salted water (approx. 20 minutes). Let the potatoes cool down a little and then cut into 2-3 cm thick slices.
In the meantime, mix the hollandaise with the cream (as an alternative to saving calories, mix milk with flour), heat and set aside.
Spread the butter on an at least 5 cm high gratin dish. Mix the potato slices, garlic and 150 grams of cheese together and pour into the gratin dish. Season the hollandaise with salt, pepper and nutmeg and pour over the potatoes. Then slide into the upper third of the oven and bake for about 30 minutes. Scatter the rest of the cheese on top and gratinate (gratinate) for 10 minutes at the same temperature or set the oven to top heat and then gratinate.