Cut the vegetables and mushrooms. Dice the mushrooms, tomato and onion. Finely chop the parsley.
Fry the vegetables. Heat the frying pan, pour in the olive oil, add the mushrooms, fry for 7-10 minutes until the liquid evaporates. Add the onion to the pan and fry until translucent for 5-7 minutes over medium heat. Stir occasionally. Add salt and pepper. Turn off the heat.
Prepare the meat. Make a pocket-shaped cut in each chicken fillet. Salt and pepper.
Prepare the dish for baking. Take a baking dish and grease it with olive oil. Put the chicken in, fill the pockets with tomato pieces. Spread the mushroom and onion mixture over the tomatoes, sprinkle with parsley. Sprinkle the dish with grated cheese.
Bake the meat. Preheat the oven to 180 degrees. Bake the dish for 25 minutes.