D.C.
Hi A.,
I agree with Susan, my daughter wasn't really into cake when she was a year old. She only ate a few bites; she didn't like the feeling of the frosting on her fingers. She never asked for a bite of the leftover cake we brought home from her birthday party. My mother-in-law works at Sam's Club, so we bought my daughter one of the smaller "smash" cakes for her to mush around. She's only recently become aware (at 19 months) that cake and candy exist.
If you really want to make his cake, here's a recipe I saw the other day. I haven't tried it (and I'm not a chocolate cake fan), so I can't give you my opinion on it.
http://weelicious.com/tag/chocolate-cupcake-recipes/
Also, I think my local grocery store carries small sugar-free cakes in the refigerated section near the bakery.