Cooked Marshmallow

A Cooked Marshmallow is a food item that grants the Well Fed buff for 10 minutes when consumed. It is unique among items in that it is not formally crafted; rather, it is created by holding a Marshmallow on a Stick over a Campfire. The Marshmallow on a Stick must be held by the player, either by attaching it to the cursor in the inventory or selecting it on the hotbar, for approximately ten seconds before the marshmallow is cooked.

Mass-producing
Because marshmallow on stick doesn't stack, it's difficult to mass-produce, but you can fill equipment with dirt or other item, one slot with cooked marshmallows and one marshmallow on a stick on quickbar. Throw marshmallow on a sticks on ground so that you can pick it up when you have free slot, select marshmallow on a stick in your quickbar, stand in front on campfire and then you can afk-produce by cooking marshmallows that stack in your equipment, and collecting one marshmallow on stick that was throwed on ground. But note that you can still stack these on max amount of 30.