Ways to make my own treats for my rats?

Okay, i don't really have anything to use as an actual treat, and I really want to train my rats and I like rewarding them when they are good. I know I can't give them anything too unhealthy and not too often, but I need some ways to make simple, not too unhealthy, but tasty treats for my three rats. I think we have yogurt but it is vanilla flavored and kinda not the healthiest. My mom hates peas so we don't have those, and I don't feed my rats peanuts anymore because for about a month or so I fed one of them liberal amounts of raw peanuts before I realized they were uncooked and i shouldn't feed them to my little ratty friends. So, nothing that has things that are rare or I may not have or anything, and if I have to cook it, please give temp. in Fahrenheit if possible.