Which of the two phrases is correct: Par excellence or per excellence

Thanks in advance

This is from www.m-w.com :

Main Entry: par ex·cel·lence
Pronunciation: 'pär-"ek-s&-'läns
Function: adjective
Etymology: French, literally, by excellence
: being the best of a kind : PREEMINENT<a salesman par excellence>

This form is correct. The term is French and the English adopted it. But it still confuses a lot of English speaking people!
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so it is par excellence.....hmmm. Thanks Nef
par excellence is usually confused with the latin per se , which means "in itself". That is why it is misspelled as per.

Can par excellence be used as a pre modifier.

I have never seen this adjective pre modifies.

Is it natural to say?

A par excellence chef instead of a chef par excellence.

Dictionaries do not indicate if there is such a limitation in using this adjective.

Thanks for your help and time
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At least one dictionary does:

adjective [never before noun] formal /pɑr ˌeksəˈlɑns/ of the highest quality, or the most typical type

a movie star par excellence.
Thanks Mister Micawber.

Your explanations are key to every problem.