I made one of those from a pre-made mix, once. It was awful - and not in the original sense of the word :-).
I’ll try your suggestion.
Well, when you are drastically carb deprived and craving chocolate, almost anything will do. I’ve had a few of those boxed ones.
There’s one that’s pretty good - has a packet of chocolate that’s kinda like thin fudge to put over it after the cake is done.