In a medium saucepan add brown sugar, granulated sugar, butter, egg yolks, and evaporated milk. Stir to combine and bring the mixture to a low boil over medium heat. Stir constantly for several minutes until the mixture begins to thicken.
Remove from heat and stir in vanilla, nuts and coconut.
For the chocolate frosting:
Melt butter. Stir in cocoa. Alternately add powdered sugar and milk, beating to spreading consistency. Add small amount additional milk, if needed. Stir in vanilla.
Pipe chocolate frosting along the outside edge of a chocolate cupcake (here's an easy tutorial. I was 9 months pregnant during this embarrassing film..don't judge ;-)).