Entree is an acceptable alternative spelling for entrée, but is used mainly in the United States while other English-peaking (and French-speaking) countries tend to retain the accent mark over the second e. However, this can be inconsistent even within the same publication and it’s best to follow one’s own preference or the appropriate style guide. It should be noted that the official entry for almost all dictionaries is entrée with the accent mark. Either way it’s spelled it is still pronounced (on tray).
Entree, again mainly in the United States, is the biggest course of a meal. Outside of the United States it is a dish served before the main course, more like what Americans call an appetizer. In olden times it was a specific meal served after the soup but before the meat dish and did not include fish.
Universally, entree can also mean making an entrance or having the ability to go in or out of a certain place.
According to Google’s ngram viewer, which is biased toward American usage and publications, entree without the accent has always been more popular and taken a leap in usage since the 1960s.
Once you’re ready for an entree, the menu offers fire roasted chicken over pumpkin puree and grilled bok choy, and a grass fed burger capped with a crunchy kimchee Russian dressing. [CBS Local Boston]
A small number of event screenings and Q&As are the entrée to a main meal of digital distribution. [The Guardian]