Quickly make a shortcrust pastry from flour, butter, egg, salt, pepper and lemon and leave to rest in the refrigerator for 15-30 minutes. Put the dough in a springform pan or quiche form, form a rim, prick and prebake at 200 ° C for 15 minutes. Cut the leek into fine rings, sauté in olive oil, season to taste and allow to cool. Mix the quark, cheese, eggs and cream and season to taste. Add the leek and spread the mixture over the pre-baked cake. Bake at 175 ° C for another 40-50 minutes.
TIP: the filling is also suitable as a leek gratin (e.g. with potatoes)!