Wash the potatoes thoroughly in cold water and brush them.
Lightly coat 4 sheets of aluminum foil in the middle with oil. Wrap the potatoes in the foil with a sprig of rosemary and thyme each. Put the potato parcels on a baking sheet in the oven preheated to 200 degrees and bake for 40-60 minutes. If you can stick a wooden skewer into the potatoes, they are done.
In the meantime, mix the quark with enough milk to create a thick cream. Season the quark cream with salt and pepper and stir in the chives.
Place the potatoes on plates, open the foil, break open the potatoes with a fork and pour the quark cream into the potatoes.