So I have a friend who is a dog trainer, has adorable Shelties and she competes in Rally (more on that later). She also makes liver treats that my dogs (and every other dog I've ever known to try them) absolutely love. So I'm passing along the recipe.
Pay attention folks - I don't think I can emphasize enough how BANANAS these will make your dog. I've known my dogs to almost tear my purse apart trying to get to some of these I accidentally left in my bag. And I make no guarantees, but I'm pretty sure you could convince your dog to do a back handspring followed by an advanced calculus problem if you promise them one of these treats.
They're great for just everyday snacks, but you can cut them up into small pieces to use for training time as well. My dogs are always much happier to work for these than they are for store-bought treats. And make sure you follow the advice she gives in the recipe - cook with the windows open. The smell from the baking treats can be pretty... stinky.
You can find the recipe right here.