Bake at 350 F for 20 minutes or until a toothpick inserted into the cake comes out clean.
Leave out uncovered overnight.
In a large bowl, combine confectioners' sugar and cocoa.
In a saucepan, heat heavy whipping cream and butter until the butter is melted.
Add the hot mixture to the sugar mixture and mix well to create a fluid, but not too runny, frosting.
Putting It Together
1 (8 ounce) package flaked coconut or a lot of white sprinkles or anything else fun that you can think of to decorate with (pink sugar hearts for Valentine's day, green shamrocks for St. Patty's day, etc.)
Place your topping into a small shallow bowl.
Remove cupcakes from liners.
Using a fork or a long toothpick or your fingers (if you've cleaned them well, are willing to get messy, and are able to resist the urge to lick them) dip each cube into the icing, then roll it in the topping.
Return the cube to its silicone liner. Continue for each piece.
Bake the Lamington cupcakes a day before you want to serve them. The cake needs to sit out overnight to get a bit stale before it is frosted. Trust me - you'll like the stale cake. Frosting it on all sides moistens it up.