In a large pot on medium high heat, mix sugar, milk, cocoa and vanilla. Stir until it begins to boil. Stop stirring and place candy thermometer along pots edge and allow to heat to 238 degrees. Once this occurs remove from heat and stir in butter. Mix until just combined and then pour into a parchment lined 10X10 inch tin and allow to cool completely. I've heard scoring the fudge a bit before it sets makes the final cutting smoother, of course I read that after I was done, but I'm just passing along that helpful info to you.
Cut into various shapes and smooth any rough edges with a potato peeler. Pierce one end with a toothpick. Coat shapes in candy melt color of your choosing and allow to set completely before decorating.
Mix frosting and scoop into a medium piping bag. Pipe decorative final ribbons. Paint after completely dry if desired. I found a small star tip makes for a perfect ruffle ribbon with one little squeeze.