Peel and wash the potatoes and cut or slice them into thin slices. Place them in several layers in a greased gratin dish (approx. 24 cm Ø) in a circle and in flakes. Spread sage leaves on top, possibly cut into strips.
Peel the garlic and press it through a garlic press. Season cream with salt, pepper and garlic. Pour evenly over the potatoes. Grate the Parmesan and sprinkle over the potatoes. Cook in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 50 minutes.
Tastes delicious as a side dish with meat.