In a bowl, add 5 tbsp of water and pour in the gelatin powder. Mix well and let it rest for about 15 minutes until it is fully absorbed.
In a large heat-proof container, add sweetened condensed milk and white chocolate. Set aside.
In a saucepan, add 118ml plus 2 tbsp of water. Pour in the sugar and place the saucepan on low heat. Stir the mixture constantly and let the mixture simmer until the sugar is dissolved. Remove it from heat and add the bloomed gelatin. Stir well until the gelatin is completely dissolved.
Pour this hot gelatin mixture into the heat-proof container oven chocolate. Let it sit for about 5 minutes so that the white chocolate starts to melt. Using a hand blender or a whisker, start blending the mixture until the white chocolate is completely melted and the mixture is smooth.
Add food colors of your choice and mix well. You can divide the glaze into portions and add different colors as well. Pass the glaze mixture through a sieve to remove any lumps and ensure the glaze has a smooth consistency.
Cool the glaze until it reaches the temperature of 32 degrees C or 90-degree F. You can place it in the refrigerator but check the glaze's temperature before pouring it.
Pass the glaze through a strainer again to make sure it is smooth and lump-free.
Now place a cake on a cup, and pour the cooled mirror glaze over the cake confidently. Let it sit for about 3 minutes so that it starts to spread across the surface of the cake. Use a hot knife to remove the drippings.
Enjoy right away or after you cool it in the refrigerator. Note to consume the cake within 24 hours as the glaze starts to lose the shine after 24 hours.