Talk to the cook and he'll say you need an egg, a pot of flour and milk.

Egg- to get the egg go across the bridge that is east then go north. There is a chicken pen there. Take the egg that is lying on the floor.

Flour- Go pick some grain in the field east of draynor and west of lumbridge. Then take it to the windmill that's north, climb up the stairs put it in the machine, pull the lever and go down stairs and collect your flour (using your pot).

milk- take a bucket and use it on the diary cow next to the chicken pen.

Go back to the cook for your reward.

reward- 300 cooking exp and usage of the cooks range.