* Note use any combination of red and green chilis, hot or mild, to suit your own taste, but use both colors. Melt 1 tablespoon butter in a small pan over medium heat. Add onion, mushrooms and chilis; cook covered until softened. Do not drain. Set aside. Season chicken breasts with salt and pepper. In a large skillet, pan-fry chicken in remaining 1 tablespoon of butter for about 10 minutes, until white, tender and semi-browned. Add onion mixture. Do not drain juices. Cover and simmer until juices bubble, about 5 minutes. Place a slice of cheese on top of each chicken breast and cover pan until cheese is melted, about 1 minute.