For the dough, first mix the flour with the baking powder, then mix with the quark, salt, 1 egg and 4 tablespoons of oil with the dough hook of the electric mixer for 1 minute.
If the dough is still a little sticky, add a little more flour.
Form the dough into a dumpling and cover and refrigerate for 30 min.
Grease the bottom of a springform pan (28 cm). Preheat the oven to 200 degrees, bottom rack.
Baking time 25-30 min For the topping, render the bacon and steam the leeks in it for about 10 min, then drain. (I did it the same way the first time I made it, but the next time I used the steaming liquid as well).
Beat the créme fraiche with the eggs, the egg yolk and the spices and stir in the Emmentaler.
Roll out the dough on a floured surface and line the bottom and 4 cm up the sides of the springform pan – prick a few times with a fork and brush with the egg white. Put the leek on top and pour the egg-cheese mixture over it.
Bake the tart immediately in the oven, covering it with aluminum foil after 10 min (otherwise it will get too dark.
Remove the foil during the last 5 minutes.
Carefully remove the tart from the pan and serve.
A leek tart in a grease pan requires twice the amount of ingredients for the same baking time.