Peel and finely chop the garlic. Peel, wash and thinly slice the potatoes. Put potatoes in layers in an ovenproof dish or on a deep baking tray (approx. 27 x 39 cm, height approx. 4 cm and approx. 3.5 litres capacity) and sprinkle with salt, pepper and garlic.
Pour cream over the potatoes and close the mould tightly with aluminium foil (or a lid). Cook in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 1 1/2 hours.
After approx. 45 minutes remove foil or lid so that the gratin can brown. In the meantime, wash the parsley and chives and shake dry. Put some parsley aside for garnishing. Chop the herbs finely or cut into small rolls.
Mix crème fraîche and herbs and season with a little salt and pepper. Cut the smoked pork loin into 10 finger-thick slices. Heat the oil in a large pan and fry the slices of smoked pork briefly, turning them until they are lightly browned.
Remove the potato gratin from the oven and place the slices of sliced pork on the gratin. Spread the herb crème fraîche on top and sprinkle thickly with cheese. Cook in the oven at the same temperature for another 30 minutes.
Garnish with parsley.