Yep, like Mimi said.
I cut the cake with a circle cutter and star tip pipe in the layers of frosting. Party City has spoons and forks that are the perfect size and are a high quality. They are about 4 inches tall.
Here's my black cloud suggestion in this scenario. If you bake and seal, this may require another HD license. Canning and manufacturing has a whole huge set of requirements and restrictions. I'm also not sure your baking insurance will cover a claim. They also have labeling issues.
One of the most dangerous froms of processing is canning. It's one thing to do this for family, but just one jar, improperly processed, can make someone extremely ill months or a year later.
For sales, I would suggest running this by your HD or Dept of Ag (which probably handles canning) and get the information from them.
Your best bet is to not get into such a high liability situation for such a small project.
I am in the process of wholesaling my vanilla extract. I have to be inspected by the FDA for the Dept of Ag because of the bottling issue (not because of national distribution, that's separate). Soon, my brother will be using my kitchen to manufacture (jar canning) his barbecue sauce recipe for sale. He has to have those additional licenses, inspections, and insurances as well.
That is why I cut the cake, add the frosting, close, and have a sticker that says keep refrigerated. But it is obviously not a canned product. It is a gimmick.