Ingredients :

• Ground beef — Use at least 15% fat. Beef that is too lean dries out during cooking and leaves a dusty gratin at the bottom. The fat melts and integrates with the cream — it provides that deep flavor you can’t quite explain but recognize immediately.
• Potatoes — Bintje or Agria preferably — starchy varieties that disappear into the dish rather than staying firm like failed gnocchi. Cut them into thin slices, around 3 mm. Too thick and they won’t cook through. Use a mandoline if you have one, or a sharp knife otherwise.
• Condensed mushroom soup — Yes, the can. No shame. It’s exactly what’s needed here: a thick texture that coats the potatoes and doesn’t evaporate in the oven. Thin it out with half a can of water or broth to ensure there’s enough liquid. Homemade fresh cream is for another recipe.
• Cheddar — A mature cheddar really makes a difference compared to mild. It melts the same but brings a slight acidity and a more pronounced taste that contrasts with the sweetness of the potato. Grate it yourself — bagged shredded cheese contains anti-caking starch that prevents it from melting well.