Place chicken breasts in a shallow ovenproof dish. Pour several inches of cider (sweet or hard) in the dish and cover. Marinate for 1 to 2 hours.
Preheat oven to 350 degrees F.
Place covered dish in oven. Cook until done, about 25 minutes. Pour juices into frying pan, stirring constantly, reduce if necessary. Add an equal amount of heavy cream. Stir constantly. Add sea salt and pepper, to taste. When thickened to desired preference, pour over chicken and garnish with chopped parsley. Serve immediately.