For the mushroom pie with crispy pastry crust, mix the flour, salt and yeast flakes in the bowl. Sprinkle the butter pieces on top and crumble the whole thing into fine crumbles.
Pour in the water and knead with the dough hooks until smooth. Refrigerate for about 40 minutes with the lid closed.
Cut the onions into coarse cubes and chop the garlic. Rinse the mushrooms briefly, clean them and chop them coarsely.
Fry the onions and garlic in the oil until translucent, stirring occasionally. Add the mushrooms and sauté over medium heat for about 5 minutes. Remove the frying pan from the heat.
Cut the camembert into small cubes and mix the egg. Stir the cheese, the egg (except for 2 tablespoons), the porcini broth, the kitchen herbs and the crème fraîche into the mushrooms. Season with salt and pepper.
Preheat the oven to 200 degrees. Line the pan with two-thirds of the dough, forming a rim of 2 1/2 cm. Prick the bottom of the dough a few times.
Pre-bake the dough base in the oven for 15 minutes and remove the foil strip. Pour in the mushroom mixture and increase the temperature to 220 degrees.
Roll out the remaining dough, wheel out strips and brush with the remaining egg. Place the strips in a grid pattern on the cake and sprinkle the thyme leaves on top.
Put the mushroom cake in the oven (bottom) and bake for about half an hour until the dough lattice is light brown.