Meaning
A black frying pan seen from above with an egg frying in it, sunny side up. Although the name is simply ‘cooking’, the picture is a fried egg, so it covers both meanings.
People use it for breakfast photos, home-cooking updates and announcing that they are finally making a proper meal: “Trying a new recipe tonight 🍳 wish me luck”. It is the egg emoji to choose when you mean fried; for a raw egg in its shell, use 🥚.