Im sorry you are wrong- Pasties were created in Cornwall and a true fact- do you know what the crimping effect is on the side of a pasty?
It was because the cornish miners who had grubby hands could hold on to the crimping and eat the pasty and throw the crimp away. True.
So in that case and taking into account the people who invented them- the way to pronounce it is par-sty. True too.
Par-sty? Get those plums out of yer mouth Bath boy.
Its pass-tee you monster.