When I first got my Scarlett, she was a very picky eater and consistently turned her nose up at any food I put in front of her. What finally got her eating was to grate some of the smelliest Natural Balance dried sausage roll over her food. I no longer have to do that-- she has turned into a chow hound like the other Cavaliers.
Try buying one of those rolls and cutting it into small pieces as a treat. I find the beef to be the stinkiest and I think that's why she liked it best. Also, how about freeze-dried raw green tripe? Your store you work in may sell that. Now that is very stinky but they seem to love it as a treat.
My Cavaliers' breeder owns a raw food company. The dogs loved the freeze dried turkey hearts- I use them as bait in the show ring and the dogs go crazy for them:
My dogs also like to chew on the trachea rings. Another good treat is raw baby carrots, though that mayh not be very appealing to your girl.
Holly, Oliver, Rosalita, and Scarlett