Q. Are menu items such as “Bananas Foster” capitalized?
A. Menu items can usually be rendered in lowercase except for any proper nouns and adjectives. For example, you might order a double cheeseburger and curly french fries followed by bananas Foster for dessert, each reflecting a named item on a menu. Only Foster, the dessert’s eponym (i.e., the person for whom it’s named, as explained in another Q&A), is capitalized.*
Similarly, you could order a Big Mac and french fries followed by a McFlurry with Oreo cookies and an iced coffee. McDonald’s applies initial capitals to all those menu items—and styles OREO in all caps—but you can follow the rules for brand names outlined at CMOS 8.69.
An exception can be made for creative or unusual names that may or may not be branded—like “Cheatin’ Vegan Nachos.” In that case, use quotation marks and, unless the item appears in lowercase on the menu, initial caps.
* Following CMOS 8.61, our preference would normally be for “french fries” (as listed there) and “bananas foster” (not listed there), but in anticipation of the forthcoming 18th edition, we’ve gone ahead and followed the entries in Merriam-Webster for both terms here (french fries but bananas Foster).