As a cautionary note, I recall many years ago snapping a head stud (it was probably defective because I was within torque limits) flush with the block. I decided to use an 'Easy Out' stud extractor to remove the stub. Well the extractor also snapped flush with the block top.
It was impossible to drill the Easy-Out stub from the block because it was tool steel.
In the end a friend had a dentist's drill which we used to drill around the edge of the stud/block, then use a small chisel to get the stud out. It was then a case of drilling out and fitting a Heli-Coil, but I had to make up,a small drill jig to ensure the tapping drill & the tap went in absolutely vertically.
I have never tried using an Easy-Out since that day about 25 years ago.