Sylvie, I made the vegetable quiche Friday night and we loved it. Thanks again for the recipe. I'm a huge fan of green beans (haricot verts) so I ran across the street and picked up a bunch to throw in the quiche.
I didn't use a pure butter ready-made quiche pastry crust, like you prefer. I think Monoprix might have been out of them when I was there. But, I stocked up on some yesterday while we were at Carrefour with the rest of the world.
While the ready-made quiche pastry crust was baking in the dish for several minutes in the oven, I started prepping my veggie of choice: the green beans.

I chopped the ends and then boiled them for 5 - 10 minutes to soften them up.

My stove needs some serious cleaning so I tried to
not get it in the photo. :)

While the beans were boiling, I mixed 4 eggs (some had feathers still stuck to the shell!), a 25 cl container of
crème fraîche (your favorite ingredient), and 25 cl of milk. Now, we
only have vanilla-flavored soymilk in our house. This tends to be a problem when a recipe calls for milk. To cut out that sweetness, I salted and peppered the mixture like crazy. For those reading this, add pepper and salt to your liking.
The pastry crust was cooked just a bit and was cooling down while I was preparing the rest of the mixture. Before dumping the mixture and beans in the crust, I covered the bottom of the crust with shredded
Gruyere cheese. Then I put the beans (of course, I drained them after the boiling process) on top of that and then I added the wet mixture. It cooked in our oven until nice and brown. Voila.

P.S. When D and I were living in the US, we used sour cream instead of crème fraîche. But, if one can find crème fraîche then all the better.