The main character's favorite food (Japanese: すきなたべもの Favorite Food) is a reoccurring theme in the Mother series, appearing on all of the initial naming screens. In all of the games, it is cooked by the respective main character's mother. It is not an actual inventory item, however, and is merely mentioned in text.
The favorite food is referenced very little in EarthBound Beginnings, being served by Ninten's mother and in Magicant, with a couple of NPCs mentioning it. When eaten, it restores the party's HP and PP completely.
In one of the "Earth Bound" prototype cartridges, the existing save file used Pizza as Ninten's favorite food. However, it is unknown whether this was a save file from Nintendo or from a previous owner. In the eShop trailer for EarthBound Beginnings, the favorite food can instead be seen as Steak, matching the sequel.
Similar to the first game, in EarthBound it is served by Ness's mother. Paula's mother also learns to prepare it as well, although she mentions that she's only just learning and still needs to practice. When eaten, it restores the party's HP and PP completely. In the letter from Ness's mother at the end of the game, she mentions that they haven't been eating his favorite food as much lately.
In Mother 3
In Mother 3, the favorite food is somewhat different. Hinawa makes it for the Lucas and Claus during the Prologue. Many villagers of Tazmily say that it was their favorite food and that Hinawa always made it for the people of Tazmily. It is also possible for a Mystery Metal Monkey to drop Lucas's favorite food, although like the "good experience" it gives, it isn't actually obtained. When hacked into the inventory, the favorite food functions as a restorative item, restoring 300 HP, as well as displaying a proper sprite, implying that earlier in development this item was planned to be usable, or was used for testing.