Piece of Cake introduces a minimalist modification that adds just one new item to the game - a slice of cake. If you craft a regular cake and place it in the crafting table, you'll receive 7 cake slices. This exactly matches the number of slices you would get from eating an entire placed cake in the world.
Furthermore, the modification allows for a reverse process: you can combine 7 cake slices back into a full cake. This can be particularly useful for transporting large quantities of cakes in a compact form, especially when using other mods that don't allow stacking complete cakes.
Cake slices are consumed almost instantly, just as quickly as eating from a placed cake. Each slice restores one hunger point, equivalent to one portion from a whole cake.
The developer is considering future updates that might include changes to pumpkin pie, such as making it placeable in the world and redesigning the current texture to represent a slice of pumpkin pie. However, these plans haven't been implemented yet to preserve the existing gameplay experience.