Prepare a form with a ring, about 8″ (20 cm) in diameter, cover with baking paper, lift the edges up just past the form's walls.
Make the instant coffee by dissolving it in 2 tbsp (30 ml) hot water. Let it cool.
Blend the biscuits in a blender, add the melted butter and stir until the mixture obtains a kind of wet sand consistency. Take it out, pour into the form while pressing very well and distributing it evenly. Leave in the fridge while you prepare the other creams.
Beat the dairy cream with the mixer to relatively stiff peaks, add the coffee, beat again. Add this to the cream cheese using a spatula to help you. Leave in the fridge.
Melt the chocolate in a water bath, while adding the warm but not hot milk to it. Stir until you obtain a homogeneous mixture. Let cool to room temperature.
For the chocolate mousse, beat the cream with a mixer; in the middle of the beating process add the cocoa through a sieve, the sugar and melted chocolate. Beat on high to a fluffy but not too firm cream (soft peaks).
Pour 1/2 the coffee cream mixture over the cooled biscuit layer, even it out. Arrange biscuits on top, packed densely, after first dipping them briefly in the cold milk with coffee.
For the empty spots where you can't fit an entire biscuit, break biscuit into a suitable size and fill the gaps, to obtain a densely packed biscuit layer. Pour 1/2 the chocolate mousse on top. Then arrange another layer of soaked biscuits, coffee cream mixture, biscuits and finish off with chocolate mousse, even it off perfectly.
Leave cake for 1 hour in the fridge.
Heat the cream and pour it over the chocolate pieces. Leave it for 1 min. and stir to a smooth consistency.
Melt the white chocolate, put it in a pastry bag with a small tip.
Pour the cooled but not yet hardened ganache over the cake as it sits in the form, then tilt it in order to distribute it evenly over the surface. Once it hardens well enough, remove the cake ring and baking paper. Don't smear the sides of the cake, leave them rustic.
Draw spirals on top using the white chocolate and use a wooden skewer to smear them and make a pattern.
Source: Tanya Doneva.
Notes: The cream is 35.5% fat.
You can increase the amount of sugar, your choice. The cream cheese was Philadelphia, natural.
I spread out the spirals of white chocolate chaotically, without any particular design in mind.