Is eating cooked food an evolved behavior or rather an intelligent one, passed down via culture?
Its almost certainly instinctual, humans along with other great apes (any many other animals) show a preference for cooked foods over raw in testing, the number that prefer it increases drastically if they are have sampled cooked foods before. So it is likely as built in as your desire for sweets and salt.
Just becasue something is instinctual does not mean you don't have to learn HOW to do it. Language is instinctual in humans, but what language you learn is up to your upbringing (the same is true in some birds), and denied another human to interact with until puberty you will not develop language. that does not make language itself cultural, just the particular language you learn.
No one would argue lions do not have an instinct to hunt, but they still have to learn how to be successful at it.
https://evolutionaryanthropology.duke.edu/sites/evolutionaryanthropology.duke.edu/files/site-images/Wobber%20et%20al_%202008_%20Great%20apes%20prefer%20cooked%20food%281%29.pdf