Roll out the puff pastry 3 mm thick and line a quiche dish with it, including the edge.
Finely chop the onions, thinly slice the leek and dice the ham. Roast everything in butter until light yellow. Let cool down.
Mix the cheese, eggs and cream, mix in the onion, leek and ham mixture, season and distribute everything on the dough.
Bake at approx. 200 ° C top / bottom heat in a preheated oven for approx. 30 - 40 minutes, until the topping has hardened and is a nice light brown color.