Hi Duke- Welcome to the world of the UnLurking
THere are two goals you want to achieve. The first is to immobilize the baked goods in their container and the second is to immobilize the container in the shipping box.
I used to ship a lot of cookies. I used coffee bean bags, placing the cookies first in baking cups and then stacking the cups inside the bag. I would fill the void in the bag with deli paper. Waxed paper would work as well.
The next trick is to immobilize the bage inside the box. I used moving/packing paper for this. It's basically blank newspaper that I get from a moving supply place. The more immobile your goods are, the more likely they are to arrive intact.
Hope this helps.