I made a batch of chicken hearts a few weeks ago. Chicken hearts, sprinkled with garlic, baked, then sliced into small pieces. Froze them into bathes in ziplocs.
Kinda slimy, but they are an often favourite and mighty cheap to make. I had Cider's attention for an entire 2 hour seminar this morning. So much so people thought we were in the wrong one her focus was so good.
I'm using up some of the older bags of treats we have, and trying to go to more natural things. Especially when meat and organs are pretty cheap and last a long time to use up.