8. Add blue and black food colouring into one of the large bowls to create a midnight blue colour. Add blue, black, and white to the other large bowl to create a lighter blue colour. Add black to one small bowl and pink and blue (= purple) to the other.
9. Once you have coloured the glaze, use a candy thermometer to make sure each bowl is still at 90ºF (32ºC). If not, heat them up in the microwave for a few seconds. If the glaze is too hot, it will be runny and won’t stick to the cake; if it is too cold, it will be too thick and remain stuck to the sides of the bowl.
10. Place a container upside down on a cookie sheet.
11. Place the cake atop the container.
12. Pour the light blue glaze into the bowl with the dark blue glaze and use a spoon to swirl the colours. (do not over-swirl, you want the colours to remain contrasting).
13. Pour this mixture over the cake and make sure the sides are covered with glaze.
14. Then take the two smaller bowls and pour the black and purple glazes on, following the lines that have already been created by swirling the blues together.
15. Once the whole cake is covered with glaze, take a large offset spatula and run it over the top of the cake to blend the colours together.
16. Let glaze dry, then run a knife along the bottom edge to get rid of the drips.