Ingredients :

• Tomme de Savoie — This is the soul of the dish. Look for an artisanal tomme if you can find it—with its grey rind and firm ivory paste. It melts without running, unlike more humid industrial cheeses. Avoid vacuum-packed versions that are too compressed: they release liquid during cooking and soak the layers.
• Smoked turkey bacon — It works perfectly in this role. Get thin slices but not translucent—too thin, they disappear; too thick, they stay soft in the middle. During baking, the edges caramelize slightly, releasing a gentle smoke that perfumes the entire creamy filling.
• Potatoes — Firm-fleshed varieties are mandatory: Charlotte, Amandine, or Nicola. No floury varieties that fall apart when cooked. They must hold their shape in rounds after two cookings—one in water, one in the oven.
• Heavy cream (Crème fraîche) — Thick, not liquid. A liquid version would make the filling too runny—it would escape between the layers before setting. A cream with 30% fat binds the eggs well and stays inside the filling.