So you want one knitted in the round? The biggest problem is going to be finding one with that size needle.
http://tiajudy.com/simplestcap.htm
http://www.bhg.com/crafts/knitting/w...ple-knit-hats/
Here's one that uses an 8, but you may be able to get away with a 9.
http://sarahditum.com/2008/10/04/fin...hallenger-hat/