Who would order just three (3) cheese balls? That certainly doesn't seem like very many - unless they are unusually large cheese balls.
Or is it "three cheese" balls?
The journalist in me tells me that the menu writer was correct in following the AP rules that specify spelling out whole numbers below 10.
The linguist in me tells me that if the menu writer had used a hyphen between the words "three" and "cheese" he or she would have avoided the bracketing paradox that makes me chuckle.
[[three][cheese balls]] or [[three cheese][balls]]