A Heartful Cake is a recipe found in Paper Mario: The Thousand-Year Door and Super Paper Mario. The cake is pink with white frosting, and has a heart on top.
In The Thousand-Year Door, Zess T. can make this recipe by mixing a Peachy Peach or a Cake Mix with Ruin Powder. Using it restores 20 FP, but if used in battle, it will soften the user's Defense, meaning they'll take more damage from enemies.
In Super Paper Mario, the Heartful Cake can be made by Dyllis of Flopside who makes it out of a Cake Mix and a Lovely Chocolate. It recovers the player's HP over time (9 HP total).