I have been told before now that my pronunciation of Italian words in English is OTT but it is actually really difficult to NOT pronounce Italian words correctly if you are used to saying them every day! I remember once my Italian husband was corrected by a waitress in England for ordering a pizza siciliana correctly as "si-chill-i-a-na" when she insisted it was "si -sill-i ana". I fell into the same trap with "ciabatta" and "bruschetta". When I left the UK they were not common words so I learnt them first with their Italian pronunciation and it feels weird to try and say them in an English way!
I know. Ever since I worked in a Greek restaurant I pronounce it moussaká (I think the boss called it moussakás, but I manage to avoid the temptation to call it that). I even had a cockney cook in our works canteen many years later "correct" me thus: "iss pronarnced moussARka".
But on the whole I do prefer to keep it British, ever since I heard someone on the antiques roadshow pronounce it "jardineer", and cafeteer is so much less affected than pretending you can speak French. And I think Jeeves pronounces the t on the end of valet. Unfortunately, I don't think we can go back and pronounce the t in chalet. I've got a friend who pronounces his Italian coffees with huge affectation even when the woman serving him is West Indian. And if that doesn't convince you, he uses the plural verb with spaghetti!
I've never heard ciabatta pronounced except in the Italian way.