Ingredients :

• Potatoes — Choose starchy varieties — Bintje, Monalisa, or Agria. They mash better and stay more compact in the mold. A Charlotte or Nicola will slide everywhere and refuse to form a real crust.
• Leek whites — Only the whites, not the green parts. They are more tender, less fibrous, and their flavor is sweeter when cooked. Cut them into 5 mm slices maximum — too thick, and they stay crunchy even after 10 minutes over medium heat.
• Heavy cream — Full-fat cream with at least 30% fat. Low-fat cream makes the filling too liquid and the quiche won’t hold up when sliced. No need for luxury cream — the one from the fresh aisle of any supermarket works perfectly.
• Grated Emmental — Grate it yourself if you can — freshly grated cheese melts more uniformly and browns better. Pre-shredded pizza cheese contains anti-caking agents that prevent it from forming a real crust.