Chop the chocolate into smaller pieces and place it in a cylinder container like a jug or a bowl.
Bloom the gelatin sheets in cold water.
Meanwhile, in a small pot, stir together water, sugar, and condensed milk and heat to a boil. Add the gelatin sheets, squeezing the excess water off the gelatin, and stir it in.
Hold the jug at an angle and pour the hot liquid down the edge of the jug to avoid creating air bubbles. Leave it for 1 min. Hold the jug again at an angle and slowly lower the hand blender to again avoid creating air bubbles. Blend the glaze together.
Place a piece of cling film over the glaze, so it touches the surface of the glaze and allow the glaze to cool until it reaches a temperature around 35ºC.
Meanwhile, prepare a baking tray with a piece of cling film. Place a cup upside down, for the cake to stand on.
Once the glaze reached the right temperature, you have to work a bit quick, add a bit of the glaze in a cup, leaving most of the glaze still in the jug. Add the white gel color to the cup and the burgundy to the jug. Stir each of them well together.
Take the mousse cake out of the freezer and out of the mold, and place it on the cup.
Pour the burgundy mirror glaze all over the cake and then add some of the white glaze and with the cold air setting on a blowdryer, blow on the glaze to give it some movement. Let the glaze drip off.
Once set, remove any mirror glaze droplets hanging off the cake with a knife and lift the cake of the cup, using two offset spatulas under the cake and gently lift over to your serving dish. Place it in the fridge to defrost for 4-5 hours.