Mirror Glaze

1. Heat the sugar, condensed milk, and 150 ml water over medium low heat
2. Mix gelatin in 125 ml water and leave to swell
3. When mixture begins to simmer, remove from heat and stir in gelatin mixture until dissolved
4. Pour hot mixture on top of white chocolate and leave to melt for several minutes
5. Whisk mixture until incorporated
6. Add food colouring
7. Cool until 90 degrees C 
8. Pour on frozen cake