One who constantly tries to add ingredients and tells someone what and how to cook something when someone is preparing food.
Mom: "Okay, i'm making dinner."
Kid 1: "No, no, no, you are making it all wrong, you need to add ketchup."
Mom: "Oh I think i can do this myself sweety."
Kid 1: "Ugh!" *adds all THEIR favorite things.
Kid 2: "OMG, you are such a backseat chef!"