Translation:You can also cook, if you want.
Why "jij" > "je"? What's the difference?
Jij is used to put emphasis on the peron performing the action. It's YOU who can cook, if you want. More info here https://www.duolingo.com/comment/3734337
Why "als je wil" instead of "als je wilt", please?
Both are fine; "willen" is an irregular verb. :)
Was is "write what you hear?". I'm tripping there every single time, because it sounds very much like he says "wil". If you translate, both are fine.