Assuming you have a stock engine, you should be okay if you get a replacement head. 

Make sure you follow MINI's spec: Spark plugs should be torqued 'unlubricated' to 27 Nm or 19.92 ft-lbs.

Thanks for the reply, I have heard this too, which scares me that if I replace head that it is just going to do it again.

Yes, it is usually the #2 that launches from the gen1 models.

I never heard an official explanation for this, but at one time, there were 'rumors' that a batch of cylinder heads were manufactured with a less than ideal alloy mix making them a little on the soft side.... 

I read this on the internet maybe 15 years ago, so take it for what it's worth... 

Need a good reliable mechanic in the Rockwall, TX area.
I have a 2005 Mini Cooper R50 Base model and the number 2 spark plug has now blown out of the head 3 times. It is literally melting the threads of the spark plug. I did not know when I bought the car that it already had a thread zert in that hole. I was told that a clogged cat system can cause this so I replaced the cat system and several other things. I replaced the head cover gasket as well as the spark plug tube gaskets. Replaced the spark plugs, wires and coil pack, as well as the PCV and several other items. I am now thinking the head has to be replaced completely, but before I do I want to make sure whatever is causing the issue is taken care of. A good mechanic that knows this engine should be able to tell me what is going on.

Thanks in advance for your help, just trying to save the old girl.