This was my littlest nephew's 3rd birthday cake, which was for his Batman-themed party. He dressed as Batman, his brother as Nightwing, and the rest of us as various villains from Batman's rogues gallery. My sister handled the decorating duties. The symbol was made by adding yellow frosting to the chocolate-frosted cake. The cake underneath is Special Birthday Cake, and the chocolate frosting is Mrs. Millman's. The yellow frosting is a simple buttercream (butter, powdered sugar, milk).