1. Preheat oven to 400 degrees F.
2. Pierce yams with a fork and roast until tender (45-50 minutes). Let rest until cool enough to handle (10-15 minutes). Cut in half, push flesh from skins, and shred with a fork.
3. Puree garbanzo beans in their liquid until smooth.
4. Gently combine all ingredients.
5. Spray a sheet pan with non-stick spray. Spoon mixture onto the pans in 1" balls.
6. Bake until golden brown (10-12 minutes).