On the day of serving make the mirror glaze. Add the cream, water, sugar, Liquid Glucose and Cocoa Powder to a heavy based pan and gently bring to the boil stirring constantly. Once boiling, reduce the heat and simmer gently for 2 minutes stirring continuously. Put the mixture through a fine sieve into a bowl and leave to cool for 10 minutes.
Meanwhile, dissolve the Gelatine according to the packet instructions. After 10 minutes, stir in the dissolved Gelatine then sieve the mixture again into a jug.
Put the glaze into the fridge to chill for about 30 minutes until still fluid but thickened, stirring every 5-10 minutes to prevent a skin from forming.
Once the glaze is ready, remove the bombe from the freezer and turn out of the mould onto an upturned bowl that is slightly smaller in diameter to the base of the dome, ensure the bombe is stable. Place a wire rack inside a deep baking tray then place the bowl with the bombe on top of the wire rack.
Take the glaze and slowly pour over the bombe ensuring it is evenly coated.