The term 'marshmallowy treat' can be summarized by two crossword solutions: SMORE (5 letters) and MOONPIE (7 letters). S'mores are a classic campfire treat made of graham crackers, chocolate, and toasted marshmallows. Moonpies are a popular snack cake made of two round graham cracker cookies with a marshmallow filling in the middle, usually covered in chocolate. Both treats are beloved for their sweet, marshmallowy flavor.