High Value Training Treats?

Hi everyone! We have an almost 6 month old cav who’s currently in puppy training classes. We are starting on an emergency recall, which we’re training with super high value treats. Our trainer suggested that these treats be exclusive to the emergency recall in order to facilitate a strong emotional response. We use beef liver as her typical high value treat and Zuke’s puppy treats for regular training. We don’t give her any people food aside from an occasional baby carrot when my brother’s dog with pancreatitis visits, so she’s not used to scraps or cheese or anything like that. What are some good options for this emergency recall training? I’ve heard of people using cheese or peanut butter, but what other foods do you use? Obviously I want to be conscious of heart health and weight control and all of those things as well, but for this particular skill I’m not too worried about if it’s high calorie or whatever.