I made this for a Whovian in a recent swap. Her 3yo daughter claimed it, because she is a Whovian too. Coolest mother ever.

No pattern sorry, I just winged it. Make a circle the size you want, back loop only around to make the brim turn, and then do your sides to the right height. I put a few increase rounds in there to make slanty sides, but it's not rocket science.