Gratin de purée de pommes de terre à la française

50 gr (0,11 lbs) mashed potatoes leftover or: 250 gr (0,55 lbs) potatoes 1 large knob butter 100 ml (3,38 oz) milk warm For gratin 1 egg 50 gr grated cheese or 1 large handful 1 knob butter salt and pepper Use 250 gr of mashed potatoes leftovers or make a from scratch by: Peel 250 gr of potatoes, cook them in a large volume of salted water and drain. Mash potatoes with a food mill or with a fork and combine them when still hot with a large knob of butter and warm milk. Adjust quantity of milk if necessary. GRATIN Preheat the oven to 200 °C / 390°F. Combine 250 gr of mashed potatoes with 1 beaten egg and a large handful of grated cheese (i.e. about 50 gr). Season. Grease a small oven proof gratin dish with butter. Pour in the preparation and bake in the oven for about 15 minutes.