Bloom gelatin. In the small bowl, add powdered gelatin and cold water 1. Gently stir with the whisk and let it sit until fully gels and hardens. You may make gelatin mass in advance and store it in the fridge for 2 days.
In the tall plastic cup, add white chocolate and sweetened condensed milk. Set aside.
In a medium saucepan, add water 2, sugar, and glucose syrup. Over medium heat, bring mixture to boil at 103oC (217oF). This is very important! Use a thermometer to check the temperature.
Pour hot mixture over chocolate and condensed milk. Add food coloring of your choice and gelatin mass. Emulsify with an immersion blender. Blend this until the entire mixture is smooth.
Split mirror glaze in smaller cups for coloring adjustment. You can add more food color for different shades at this point.
Pass mirror glaze through the sieve to remove any gelatin and food coloring clumps.
Allow the mirror glaze to cool to "working temperature", which is from 28oC ( 82oF) to 34oC (94oF), and pour over the cake or mini cakes.
Notes
When glazing the cake, place plastic wrap on the table and a tall glass jar or cup.Try not to make many bubbles when emulsifying with an immersion blender. Pop any bubbles with a toothpick after glazing the cake.