The welding trick is best but I try to build up a bit of weld on the exposed stud first, try and get at it from all angles attaching weld where you can, even with a flush stud you can build up a dome of weld on top.
A mig is best as it is most controlable.
This also gets some heat on the job, then slip a much larger diameter nut over the welded stump and weld the two together, the bigger nut alows more weld to grip the stump even down the sides.
By this time you will have enough heat from the welding alone, next rock the nut back and forth looking for any movement do not be greedy and wind it out in one movement, go little by little the stud will wind out. Never failed me yet
Lastly never had any luck with an easi out dont go there. :'(
