Cooking. That is an EX Job mostly for cooking food. They give buffs, heal, and fill your hunger meter. It's a very good EX Job with consistent usage.
However, I think this will the best EX Job that will be very useful in the Luminous Expedition that will be coming soon enough and I am not kidding when I said this is going to be beneficial.
In Alternate World, all players can cook even without the EX Job Chef or Cook. However, the difference between the player without the EX Job and the player who has the Chef or Cook EX Job is that the one who has no EX Job is more likely to produce a failed dish, or if they succeed, they will have a very poor quality of food. As for the players who have the necessary EX Job, it is clear they will be more likely to succeed in cooking and at times, they have the ability to produce new dishes according to how they wish.