For base Grind the biscuit in powder.
Take the powder in the bowl and adf melted butter in it and mix well.
Grease the mould well, spread the biscuit mixture in the mould evenly, keep it in freeze for 10 to 15 minutes until it sets.
Melt dark chocolate add milk (room temperature) gently stirbthisbtill everything is well combined, let this come to room temperature.
Similar to the dark chocolate melt white chocolate gently add milk (room temperature) ,. gently mix it well. It tooks long time compare to dark chocolate.
Whip the cream add the dark ganache, mix well.
Add it to the mould and spread it evenly with the help of stapula, place it in the freeze not freezer for 15 minutes.
Whip the cream add white ganache and mix well.
Pour this white chocolate mousse over the dark chocolate mousse and spread it evenly with the help of stapula, cover it with cling film and place it in freeze for minimum 2 hours.
After 2 hours tap the sides of mould and gently open the sides.
Decorate the cake with coco powder as desired.
