Start by preparing the leavened dough, the day before or the same day, several hours in advance (ideally 4 hours).
Mix the yeast with the tepid milk. Stir to dissolve the yeast well and let it rest for 10 minutes.
In a large bowl, pour the flour, make a well, and add the salt, eggs, yeast, and soft or melted butter in this order.
Mix the ingredients well, and beat by hand, or with a mixer with kneading hooks, for about 10 minutes. The dough should become elastic and detach from the hand. Sprinkle the bowl with flour if necessary.
Once the dough is well kneaded, put the dough in a bowl lined with baking paper (or at least floured).
Cover the bowl with a clean cloth and put it in a warm room or over a radiator. Let it rest. The dough must double in volume (count between 2 and 4 hours depending on the temperature - I let it rise for 4 hours).
If you make the dough the day before, you can put it in the bottom of your refrigerator, but take it out early enough the next day (about 2 hours) to warm it up (put it on a radiator for example).
Once the dough has risen, place it with baking paper in a large pie dish (I took a 30 cm diameter dish).
Lower the dough on the paper with your fists to stretch it towards the edges. It is not necessary that the dough goes up all the way to the edges.
Preheat the oven to 200 °C.
Thinly slice the maroilles and cover the entire dough. Season generously with pepper.
Coat the maroilles with a thin layer of thick crème fraîche (2 tablespoons, no more).
Bake 20 minutes at 200°C and then 10 minutes more at 180°C. If the pie becomes too brown, you can cover it with a sheet of baking paper to finish baking.
Enjoy the warm tart, serve it with a simple green salad or endive salad, and with a good Northern beer of course.