We use peanut butter and the spray too.

The best thing to do is the dog biscuits (probably near the kong toys) that are flat and shaped like a small kong. You just squeeze the sides so the hole is oval then you put the treat in. It makes them nuts because they can see it and smell it but it's really hard to get out. Riley is smart about it though, she throws it around the house and tries to somehow break the biscuit