Cover round cake with yellow fondant; smooth. Cut white fondant circle with wavy edges; position on cake top. Divide round cake into 8ths, marking 1 1/4 in. from base of cake. Pipe tip 4 double drop strings in royal icing from division points, 1/2 and 3/4 in. deep. Add tip 2 dots at string points. In buttercream, add tip 4 bead bottom border; attach bows. Position candles.