If she insists on getting you something maybe you could just go with the healthiest option? Does Domino's have subs? I can't remember. But a turkey sub isn't a bad option.
Free food is hard for me to turn down

. And I also have a hard time asserting myself against employers. It's hard to do when they don't take "no" very well...that being said I'm kind of impressed your boss splashes out that much cash to feed you guys. My boss won't even give us coffee for the coffee maker. We have to get a collection going...