Sometimes less is more, and sometimes more is tastier. It depends. Here we are dealing with the second case!
Clean the button mushrooms and grate coarsely. Also grate the cheese. Finely chop the onion and garlic. Glaze the onion and garlic in a frying pan. Add the button mushrooms and cook it all until the mushrooms are half their volume. When this happens, remove from the heat source and set aside to cool. Mix the cooled mushrooms with cheese and chopped parsley, and season with salt and pepper. You can additionally add chopped spinach.
Cut the chicken fillet lengthwise with a knife so as not to cut the meat completely. Unfold the meat like a book. Season with salt and pepper. Put 1–2 tablespoons of the stuffing in the middle and roll it up carefully. Wrap the prepared meat with bacon slices.
Put the chicken in the oven preheated to 200 °C for about 20–25 minutes. The bacon should lightly brown.
Serve with lunch garnish.