Form steaks from the chicken breasts and gently tenderize them. Combine the beer, mustard, olive oil with spices and marinate the chicken for 40 minutes. Arrange it in a tray and add a little more olive oil and a little more beer. Roast the meat in foil.
Heat a little olive oil and the butter in a pan. Put the cleaned and sliced mushrooms to sauté until tender and add 2 cloves of crushed garlic.