Make layered cake. Prepare batter following recipe directions. Stir 2 ½ tablespoons jimmies into batter. Bake cake layers in pan set and allow to cool according to pan package directions. Level cake layers.

Ice cake. Place a cake layer, cut side down, on cake circle. Use spatula and white decorator icing to ice top of layer smooth and stack next layer. Continue icing and adding layers until cake is stacked. Use spatula and icing to ice cake smooth.

Make fondant balloons. Tint 1 oz. white fondant each dark orange, red, dark pink, blue, teal, green and yellow. Combine Orange with Red-Red for dark orange shown. Combine Pink with Violet for dark pink shown. Combine Moss Green with Buttercup Yellow for green shown. Combine Buttercup Yellow with Leaf Green for yellow shown. Use fondant roller with pink guide rings to roll out each color, separately, 1/16 in. thick. Use straight side of round cut-outs B, C and D and straight side of oval cut-outs A, and B to cut shapes from each color of fondant. Use knife to cut triangle balloon knots, each 1/4 in. x 1/4 in.

Create balloon pattern before placing on cake. Working on 19 in. surface, begin with the bottom layer of balloons, which will be 3 in. from top of cake. Use knife so balloons inlay as needed. Create the top balloon border, inlaying as needed, and cutting tops straight.

Decorate cake. Use tip 2, a cut disposable decorating bag and icing to attach balloons and knots following pattern. Tint small portion of decorator icing gray. Use tip 2, a cut disposable decorating bag and gray icing to pipe balloon strings and ties.