Season the chicken fillet with salt and pepper and fry briefly in the pan with the onion and the garlic and the diced carrots. Then add the peas and mushrooms .... I used the mushroom water so it tasted nice and mushroom (of course not for everyone) you can also add a little vegetable broth and let everything simmer for 5 minutes and let the cheese melt in at the end ,,,, gives a great bond and a nice cheesy taste .... you can also omit the cheese and instead Bind with a little roux and finally stir in the parsley, if necessary, season with a little lemon juice and serve with the tomato spaetzle.