Mix the flour with salt and RUB with your hands and butter until crumbs. Add the egg and knead the dough. If it does not roll into a ball, add a spoonful of cold water. If it is too soft, add a little flour. Put in the refrigerator for 1 hour.
Cut the mushrooms into slices and fry in oil until the liquid evaporates. Season with salt and pepper.
Cut the leeks into rings and rinse with cold water, let it drain well. Cut the meat into strips.
Put the filling ingredients in a bowl, add salt and pepper to taste, and beat lightly with a whisk. Grate the cheese on a coarse grater.
Take the dough out of the refrigerator. Grease the form with oil. Roll out the dough a little, put it in a mold and knead it with your hands over the entire surface, making a side. Repeatedly prick with a fork and put in the preheated oven for 15 minutes.
Remove and arrange the meat,
Then mushrooms and onions.
Pour the filling evenly, top with cheese and put it back in the oven. Bake at 180-200*C for 25 minutes.
Remove from the oven, cover with a napkin and let rest for 5 minutes.