A lonely little girl makes a new best friend from her favorite foods—marshmallows and peanut butter.
Ten-year-old Bethany wants to make new friends. She sneaks into her father’s marshmallow factory, leaves the machine on all night, and turns out a huge marshmallow. Once Bethany makes a peanut butter face on it, her dad can’t destroy it. The marshmallow wants to be Bethany’s pal, and he’s accepted into her home, becomes her new best friend, and even wins her more friends at school.
Bethany Buttercup, age 10, wants to make new friends and gets the bright idea to leave the marshmallow tube on overnight in her father’s factory, creating a puffy white friend as big as a snowman. Bethany creeps through the window into her father’s factory and turns on the machine, which creates a marshmallow larger than human size.
In the morning her dad finds out about it and says she was caught on video, so don’t deny it. Bethany suggests that she come with her father to the factory. Upon arrival Bethany jumps out of the car with her jar of peanut butter and runs onto the factory floor. She paints a personality face on her new marshmallow-cotton ball friend. She is in awe, but her father overreacts again in shock. Her father threatens to hose it down with water but the Marshmallow suggests that he become Bethany’s pal. Her dad reluctantly agrees, but says he will roast the marshmallow at a campfire if he causes his business any problems.
The Buttercups make Peanut Butter Marshmallow welcome in their home. Peanut Butter Marshmallow and Bethany do everything children do with their best friends. If anyone bullies Bethany, the Marshmallow rolls them right out of the way. When he comes with her to Best Friend Day at school, Bethany is the most popular girl in her grade. Despite all, Mr. Buttercup comes to love Peanut Butter Marshmallow and even creates a line of special marshmallows with peanut butter filling. Of course, Bethany takes the credit, for without her insistence on creating a new best friend, no one would have ever eaten peanut butter marshmallows.