First make a shortcrust pastry from rye and wheat flour as well as butter, sugar, a pinch of salt and 1 egg and put it in the refrigerator for at least 30 minutes.
In the meantime, clean, peel and cut the vegetables. Stew the leeks, carrots and sweet potatoes in a saucepan with a little water for about 15 minutes.
Grease a springform pan (26 cm) and dust with flour. Roll out the dough and place in the mold (including the edge). Drain the vegetables and then spread them on the dough. Place the bacon cubes on top. Whisk 3 eggs with cream, milk and grated cheese (sprinkled cheese and Parmesan) and pour them over the quiche evenly.
Bake at 200 ° C in a preheated oven with top / bottom heat for 30 minutes until the quiche turns brown and the egg mixture has hardened.
After baking, take the quiche out of the oven and let it cool for another 5 minutes and then stock up.
Cut the quiche into pieces and serve with a green salad.