I saw this in a candy shop a few weeks ago. Cake boxes filled with candy! They had all different sizes of cake boxes and the clear covers let you peek inside. I would tie with baker's twine for a more authentic look. There are some really cute cake boxes out there!
I have kids that don't love cake (I cannot relate) and I think this is a great alternative! Fill it up with the birthday boy's favorite candy but it still seems cake-ish!