The Frosty Pine Nuts is a fan-made grub that can be obtained in the Miitopia Tales DLC.
Frosty Pine Nuts
It's a bowl of pine nuts with milk, making it look like a bowl of cereal. A spoon is placed in it. It fills 50% of the stomach.
It's considered to be a Very Rare grub much like certain grub like Cheesecake. As this is a unique grub obtained from a tale, it's immediately transferred to the main story after the stage featuring the monster that drops it is cleared once (per tale playthrough), rendering it unusable by the tale's main character unlike other grub.
A sweet bowl of cereal. Giving it the "Frosty" name allows us to stay out of trouble.