Whisk the Dawn® Supersponge Cake Mix – Plainand water for 1 minute on slow speed, scrape down and then divide equally amongst 6 bowls. Add 5g of food colouring to each bowl ensuring you have 6 different coloured batters, and then whisk each bowl on high speed for 11-12 minutes. Scrape down and whisk for a further 2 minutes on slow speed. Place each coloured batter into a round tin lined with baking paper.
Bake each at 200°C for 10-15 minutes and allow to cool.
Once you have all of your rainbow sponge layers sandwich them together with Dawn® Vanilla Frosting and then cut to size once chilled or, if preferred, cut each of the sponges to size first and then sandwich the layers together. Heat Dawn® White Fudge Icingto 40°C-50°C and pour over the top of the cake, smoothing with a palette knife and push at intervals off the top edge of the cake to give a rustic running finish.
For an alternative finish cover the cake in white fondant icing and decorate the top with silver edible balls.