Who plays 13 year old princess bubblegum?

In the animated series "Adventure Time," the character of Princess Bubblegum is voiced by actress and musician Pendleton Ward. However, when referring to the character's younger version, a 13-year-old Princess Bubblegum, the voice is provided by a different actress, namely, "Donny" McMahon in the episode "It Came from the Nightosphere." The character has become iconic for her intelligence and leadership in the Candy Kingdom.