Cut the onion into small cubes, fry in vegetable oil until golden brown. Chop the mushrooms finely and fry with the onion.
Grind the chicken breast. Add mushrooms, fried with onions, mix. Grate the cheese, mix a third part with chicken and mushrooms, leave the rest for sprinkling on top.
Add sour cream to a mixture of chicken, mushrooms, and cheese, beat in an egg, mix well, and salt to taste. Grease a baking dish with butter, roll out the dough and distribute it evenly over the bottom of the form, making the sides 1.5-2 cm. Put the filling, smooth, and sprinkle with the remaining cheese on top. Place in a preheated oven and bake for 20-30 minutes, until the cheese melts well.
Drain the water from the olives, cut them into thin slices. When the cheese is melted on top of the pie, remove it from the oven and sprinkle generously with chopped olives. Place in the oven for another 5 minutes and turn off.