We don't say spaghetto for one though, do we? Paninis is Anglicised. Probably pizze is the correct plural of pizzas, but we don't say 'I'm shoving a couple of pizze in the oven' do we? I would stick with paninis. Life's too short.
I saw plateau pluralised to plateaus yesterday, which really annoyed me. Imagine doing that with chateau or gateau! life as we know it would end Like I said, life's too short. Stick with the Anglicised way