Mix cake according to manufacturer’s instructions. Deposit 1 lb. batter into sprayed and papered 8-inch cake pans. Bake at 350ºF until cake springs back lightly when touched. Let cool completely. Fill, crumb coat, and smooth ice with white buttercreme. Make light yellow by combining bright yellow and white buttercreme at a ratio of 5 parts white to 1 part yellow. Pipe generous portions of hot pink, light yellow, and white buttercreme around the sides and top of cake, alternating colors to ensure marbled/swirl effect. Smooth ice. Mix together golden yellow and flat icing. Pipe around edges of cake and then into center to create a drip and cover the top of the cake. Decorate with blue buttercreme, fresh flowers, and pink macarons.