This Rainbow Faultline Cake is literally bursting with color! Made by combing buttercream, then filling in the gaps with tinted icing, this faultline cake is great for celebrating almost any occasion. Big enough to serve at a large birthday party or baby shower, this cake is a great way to impress your friends and family.
Bake cake. Prepare cake batter following recipe instructions. Bake and cool four cake layers. Trim one layer to 1 in. high. Level other three layers to 2 in. Fill and stack for 7 in. high cake.
Ice cake. Using white icing, ice sides of cake smooth. Using notched side of comb, start at bottom and comb straight up sides of cake. Repeat until all sides are combed.
Tint icing. Tint ½ cup white icing each pink, orange, yellow, green, teal and purple using color combinations provided. Combine Pink and Rose icing colors to get pink color shown. Combine Orange and Lemon Yellow icing colors to get orange color shown. Combine Lemon Yellow and Golden Yellow icing colors to get yellow color shown. Combine Lemon Yellow and touch of Leaf Green icing colors to get green color shown. Combine Teal and Kelly Green icing colors to get teal color shown. Combine Violet and Rose icing colors to get purple color shown.
Using Royal Blue icing color, tint ½ cup white icing blue. Reserve remaining icing white.
Fill in lines. Prepare seven decorating bags separately with pink, orange, yellow, green, teal, blue and purple icing. Cut ½ in. off tip of each bag.
Alternating colors, fill in notches on sides of cake. Using icing smoother, start at bottom of cake and swipe up, smoothing each side. Repeat, cleaning the smoother off before each swipe, until sides are smooth.
Using icing smoother or spatula, carefully swipe excess off of top of cake.
Reserve remaining icing.
Decorate cake. Using 9 in. spatula and white icing, ice top and bottom of cake, about 2 in. wide, leaving middle of cake showing. Using icing smoother, smooth out icing.
Prepare seven decorating bags with tip 12. Fill separately with pink, orange, yellow, green, teal, blue and purple icing. Pipe dots along top edge and around bottom of cake, alternating colors.