This episode is based on the fourth story in the Goosebumps book 'Still More Tales to Give You Goosebumps'.
The story in the book is different then the episode, in the book, the one boy eats the cookie anyway instead of giving it to his brother, also in the book, the Aunt is a witch that goes around claiming to be related to families as a Great Aunt so she can rapidity age their children and teens to old men to marry them off to her elderly friends. In the book, there is a girl that Tom has a crush on, named Becca is in the book, but she is not in the episode.