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I just read this on wikipedia - Interesting!!!

vanilla slice, custard slice, also known as the Napoleon, is a French pastry whose exact origin is unknown. Its modern form was influenced by improvements of Marie-Antoine Carême.

Source: https://en.wikipedia.org/wiki/Mille-feuille

Thank you I have heard and ate a Napoleon. What a treat from your coworker. Sorry for being lazy, I should have looked it up. Have a good day.