Sprinkle the chicken breasts on both sides with salt and pepper.
Drop the garlic into a small saucepan of boiling water, cook for 5 minutes, and set aside. When cool, peel of the skins.
Heat the butter in a heavy skillet and add the chicken pieces. Cook over medium high heat for about 1 minute, or until lightly browned on one side. Turn and cook for about 1 minute on the second side.
Add the mushrooms and cook, turning chicken occasionally, for about 2 minutes.
Add the shallots, garlic, Port wine, tomatoes, and seasonings: Cover and cook for 10 minutes, or until the chicken is cooked through to 165°F in the thickest part of the breast. Transfer the chicken, mushrooms, and tomatoes to a warm platter. If the sauce is too thin, cook it down for a minute or two. Pour the sauce over the chicken and sprinkle with chopped parsley.
