Treat recommendations

We have such a picky eater when it comes to food. We've tried giving her meats, cooked and raw, different treats but she literally is like a baby and will refuse. We've implemented it into her food but no matter how often, what ways, she just refuses all. We have learned tho that she lovessss crackers (very sneaky of her every time) are there any cracker like treats on the market that are safe for ferrets? Every other option has been exhausted and we want to try something different and give her treats like her sister but she truly refuses every single time. Please any recs so we can broaden her horizons while still being careful of her preferences