This is a simple, classic dish that for some reason has become rare. It appeared in one of Elizabeth David's early books, French Country Cooking, and for a while was a standard on bistro menus; perhaps it carries an unflattering association with check tablecloths and coq au vin.
I have not given quantities. You will know how many potatoes and how much butter you want for each serving. You could slice the potatoes into water before layering them; but some starchiness is pleasing in this dish, as it is in gratin dauphinois.
Waxy potatoes, such as Charlotte
Butter a gratin dish. Peel the potatoes. Cut them into rounds, arranging them in the dish; when you have a layer, cut slivers of butter and place them on top, and grind over salt and pepper. Build the layers of potato, butter and seasoning.
Cover the dish loosely with foil, which will help the potatoes to cook by steaming them. Bake at gas mark 4/180 C for 45 minutes; uncover the dish and bake for another 30 minutes, turning up the heat if the top layer is not browning.