Place chicken in dry pan (see searing instructions above). Let cook for 4-5 minutes on each side until cooked through and meat thermometer reaches 165 degrees. Remove from pan, cover and keep warm. Add 1 tablespoon of butter to hot pan and toss in mushrooms. Brown for several minutes. (do not salt it will keep mushrooms from browning). Once your mushrooms are as brown as desired, add a big pinch of salt and pepper. Add garlic and sauté for 3 minutes. Add flour and cook for about 1 minute. Add chicken stock, salt and pepper to taste. Serve sauce over seared chicken.