Cut the mushrooms and braise them in a pan with butter. In the meantime, cut the chicken breasts into bites, then add them to the mushrooms.
Salt them and fry until golden. In the meantime, beat 4 eggs and 1 2/3 cups yoghurt. Pour cold water into the yoghurt cup for later.
Pour oil at the bottom of the pot you intend to cook the fricassee in. Once it heats up enough, add 3 tbsp flour. Stir vigorously until you get a homogeneous mixture.
Make sure there's no lumps left. Pour in the prepared egg/yoghurt mixture, then immediately pour in the cold water. I like to squeeze in half a lemon, to prevent it from curdling, because this has happened to me before.
Keep stirring nonstop until you obtain the desired density. Add salt and black pepper.
Keep in mind that when it cools it's going to thicken more. If you like, you can pour in all the mushrooms and meat in it.
But if you'd like it to look more elegant, arrange them before serving.