A method of forming a component having an internal passage defined therein includes positioning a jacketed core with respect to a mold. The jacketed core includes a hollow structure that includes an interior portion shaped to define at least one interior passage feature of the internal passage. The jacketed core also includes an inner core disposed within the hollow structure and complementarily shaped by the interior portion of the hollow structure. The method also includes introducing a component material in a molten state into a cavity of the mold to form the component, such that the inner core defines the internal passage including the at least one interior passage feature defined therein.