I would call it an amuse-bouche, and keep the French pronunciation.
When talking about cooking, fine dining, arts, and cinema in particular, there are a ton of words and phrases that have been borrowed from French that you would say as the French would, such as "mise-en-place," "mirepoix," "entreé," "montage," "avant-garde," etc. American pronunciation (if that's what you're going for) is all over the place, and there are many words that were originally French that may be pronounced differently in English, BUT in general, my advice is to pronounce it as the French would and you'll be fine!
Hope that helps! :)