4 potatoes, like Yukon Gold, peeled
Clarified butter, warmed
Fresh thyme leaves
Salt and freshly ground pepper
Preheat oven to 400 degrees.
Slice the potatoes very thinly, by hand, or with a mandoline. In a large gratin dish, layer the sliced potatoes, brushing every layer with butter. When half the potatoes are in the dish, sprinkle with salt and pepper and thyme leaves, then continue layering potatoes. Pro. Tip: save the prettiest slices for the top layer.
Bake, uncovered, until golden brown, about 45 minutes. Or, when cooking at 325 (alongside Prime Rib), adjust cooking time to one hour, or until the gratin is golden and bubbly.
1. Sprinkle top with ½ cup freshly grated Gruyere cheese. Pour in ¼ cup heavy cream or even crème fraiche.
2. With 1/4 lb. smoked ham and 2 cups Gruyere cheese: Arrange half the ham strips evenly over half of the potatoes and distribute half of the cheese over the ham. Season with nutmeg, salt and pepper. Arrange the remaining potatoes, ham and cheese in even layers. Dot the top with butter. Bake uncovered at 400 for 50 minutes. Do not overcook.