When the plug snaps like that I think it leaves the threaded part in the engine with it's ceramic core. Be carefull when whacking anything down the middle of the plug that you don't push that bit of ceramic into the engine.
I've heard people suggest that if you turn the engine over the pressure should blow that ceramic core out.
If you can get that ceramic bit out of the middle, I would be tempted to attack it with a torx bit in an impact driver with lots of penetrating fluid or get an easy-out on it.
Either way give it a good soaking in penetrating fluid as your plug looks well corroded.
Alternatively if you take the head off (a bit more of a ball ache than it sounds) you'll be able to unscrew the plug from the other side with some long nose pliers.
If you ever do get the old bit of plug out, don't forget the spark plug washer which might still be in the top of your engine!
I've heard people suggest that if you turn the engine over the pressure should blow that ceramic core out.
If you can get that ceramic bit out of the middle, I would be tempted to attack it with a torx bit in an impact driver with lots of penetrating fluid or get an easy-out on it.
Either way give it a good soaking in penetrating fluid as your plug looks well corroded.
Alternatively if you take the head off (a bit more of a ball ache than it sounds) you'll be able to unscrew the plug from the other side with some long nose pliers.
If you ever do get the old bit of plug out, don't forget the spark plug washer which might still be in the top of your engine!
-suck-squeeze-bang-blow-