Nope! Not an accident. I read a chocolate cake recipe in a magazine that used cayenne. I was in the dentist office, I think, and I meant to copy it but they called me in.
Then there was a recipe on TV for Chocolate Zucchini cupcakes that had cinnamon and they were good. I wrote down 2 tsp. of cinnamon for the cupcakes, but my husband swears they said 2 Tbsp. I used about 3 tsp.
You couldn't taste either pepper or cinnamon in the cake, but there was an enhancement. I promise, it doesn't ruin the cake.
I had an authentic Mexican cookbook that had a chili recipe using cocoa powder, soooooooo.......I imagine those of you from Mexico know this.