Brush the potatoes thoroughly under running water. Cut the potatoes in half and hollow them out to a small edge with a ball cutter (the potato pieces that are released can be used for a soup, for example).
Place the potatoes on a baking tray lined with baking paper. Sprinkle with some salt and pepper. Dice the raclette cheese and place in the wells. Bake the potatoes in a preheated oven at 200 degrees (gas: level 3-4, fan oven: 180 degrees) for about 20 minutes.
Press one prune lightly into each cheese and serve sprinkled with cress.