From the Essential Pépin tv series, Episode 106: Special Spuds
This dish is my version of a classic from my youth. My mother always makes her gratin exclusively with milk and tops the potatoes with grated Gruyère cheese before baking. Sometimes I use grated cheese in this dish, but other times I don’t, depending on my mood.
It is important not to rinse or soak the potatoes after slicing them. Rinsing would remove most of the starch, which is needed to thicken the mixture as it comes to a boil on top of the stove.
The gratin goes well with a salad of frisée or escarole dressed with a mustardy garlic dressing. One of the greatest treats of this dish are the leftovers, which can be enjoyed cool or at room temperature the next day. —Jacques Pépin
Serves 6 to 8