These were meant to be cupcakes but turned into muffins as I miscalculated the flour. Adding chillies to the batter mix worked really well: it gave the hint of a warming kick without being overly spicy and was a lovely contrast to the chocolate butter cream. I think this would work really well as a rich chocolate chilli cake with a fudge sauce/icing.
I added a finely chopped (or whizzed) chilli per egg into a normal batter recipe as I creamed the butter and the sugar.
You rip what you sew!