I made Cosmic Brownies a few weeks ago. Just a basic brownie recipe, made from scratch. Spread with Chocolate Ganache, or one would go for chocolate buttercream or just plain melted chocolate. And topped with Mini M&Ms and chopped walnuts.
A quick tip when baking with chocolate. Add a little instant espresso powder to the batter. It somehow makes the chocolate tastes more, well, chocolatey.