R.R.
Cute idea...a dear friend of mine did this when I had to have a hysterectomy, a "Farewell to Your Uterus" gift box. OK, I digress, it's late, lol ; )
I would substitute cookies for the cupcakes, I send those cross country and I've never had a problem with them. Where is the package going? If to a warm destination I would make sure to pack the chocolate bars well, and place in the center of your box. And a birthday card❤