My Mum's Flamiche aux Poireaux (Leek Tart)

Flamiche aux poireaux is a typical dish from my region in France, Picardy. It has one main ingredient, leek.
I can not count how many times I have had it at home (Mum's is always the best), and then made it myself. At some point I loved it so much that I made it every Sunday for dinner.
You can find many different recipes of the Flamiche aux poireaux online, but none of them are like the one I use. For me, the prefect leek tart should not have any bacon, cheese and in the preparation, nothing like eggs and cream as this would make it a quiche. I only use leeks, flour and milk and it make a delicious creamy tart!
It is way better to use a homemade dough, enough for 2 tarts, because the tart should be covered with pastry too. I usually cover mine only with stripes of pastry because I think it is too much dough (but that's my preference). I served it with chicory, which is also something we eat a lot at home :-) It's a home day!

Ingredients:
3/4 leeks
milk
2 tbsp flour
salt, pepper and optional: paprika or nutmeg

Preheat the oven to 200°C. Clean and cut the leeks very thin. Cook them slowly in a large saucepan until they get translucent and soft. You can leave a lid on and let them cook on low heat for 20 min. Once they are ready, add the flour, enough to absorb all liquid in the pan and from the leeks. Then add milk little by little and stir. The mixture should thicken. Add more milk and stir again.. repeat until you get enough mixture to cover your tart dish. Season to your taste. Another option is to add some Gruyere with the leeks and let it melt all together.
Line a tart dish with brisee pastry. Pour the leek mix onto it. Cover the leeks with another pastry (or not).
Bake for about 40-45 min, until the tart edges become golden brown. Serve right away. Bon apetit. Enjoy this "north of France" dish.