I present Caramelized Onion and Mango Upside-Down Cake:
Sometimes when you improvise when you cook it comes out well (e.g. this previous post). Sometimes, unfortunately, you end up with something you regret making.
It was supposed to be a rhubarb upside-down cake, but mutated into the unpleasant-looking caramelized onion and mango upside-down cake you see here.