Bake your favorite cake recipe or mix in the Ice Cream Cone Pan following recipe instructions. Cool in pan on wire rack 10 minutes. Remove from pan and cool completely. Arrange cake on foil-wrapped cake board cut to fit.
Tint buttercream icing light yellow, dark yellow and rose. Outline waffle pattern on cone with dark yellow icing using tip 3. Fill in between outlines with light yellow tip 16 stars. Using spatula, ice bottom "ice cream" scoop, then repeat to create top scoop. Sprinkle with rainbow jimmies.