Take a punch and dimple the center of the broken bolt, this will help your drill start. Use a new bit that is the correct size for the smallest EZ out you can find. Keep your drill tip wet, WD will work OK. Drill straight, you don't want to get into the threads on the sides, go no deeper than you have to to get the EZ out to bite. Chuck the EZ out into a tap handle, blow the hole out so there is no debris in the threads, give 'er a little squirt of WD and you should be able to twist that SOB outta there with little force like Paul suggested.
Steve