Absolutely. Google previously had a direct link to the full-size image, but it has removed this due to potential legal issues. See [0].
> Is that a violation if the bakery didn't advertise it?
According to Disney, it is. See [1].
> Any privately commissioned art?
Not any art, no. Only that which uses IP/material they do not have a license to.
[0]: https://www.ghacks.net/2018/02/12/say-goodbye-to-the-view-im...
[1]: https://en.wikipedia.org/wiki/Cake_copyright#Copyright_of_ar...
Which is why e.g. Bethesda is not going to slap you for your Mr House or Pip-Boy fanart, but will slap the projects that recreate Fallout 3 in engine X.