I always imagine multi-tentacled cooks preparing various stages of the same dish at the same time in order to prepare great quantities. When I make spaghetti sauce, I cook the meat/veggies first, prepare the tomato base next, and then simmer the two for x amount of time. A multi-tentacled cook would be able to chop the garlic, mince the onions, prepare the meat and tomato base, presumably all at the same time. (I'm assuming the being in possession of the tentacles would be capable of concentrating on all these different things. I do know that octopi are quite intelligent, but in my readings, they've all come across as rather single minded. They can use their tentacles to unscrew jar tops.)