Finely chopping the chocolate results in small shards that won't sink in the batter. Use a spring-loaded ice cream scoop to transfer batter to muffin cups with ease.
Be sure cupcakes are completely cool before decorating, to avoid melting the frosting.
Icing on the (Cup)Cake
You don't need fancy supplies to frost these treats -- a zip-top bag makes a fine stand-in for a pastry bag. Place it in a tall glass so it's easier to fill.