Line a springform pan 24 cm in diameter with parchment paper.
Cut the leek lengthways, clean, wash and cut into rings. Heat the olive oil in a pan and steam the leek for about 5 minutes.
For the shortcrust pastry, knead the flour, salt, eggs and cold butter in a bowl. Shape the dough into a ball, wrap in cling film and put in the refrigerator for 1/2 hour.
In the meantime, grate the Gouda for the topping and cut the ham into 1 x 1 cm cubes.
Mix the eggs with the cream, cornstarch and Gouda. Mix in the slightly cooled leek and the ham cubes and season with salt and pepper.
Roll out the shortcrust pastry and press it into the springform pan, pulling up about 3 cm on the sides. Put the leek mixture on the dough and place the quiche in the preheated oven at approx. 200 degrees top / bottom heat and bake for approx. 35 minutes.