Line 2 ring moulds with parchment paper.
Halve the sponge cake and cut the halved cake into roundels using a medium size cookie cutter.
Roughly chop 100 grams dark chocolate and transfer into a bowl.
Heat ½ cup cream in a non-stick pan and bring to boil.
Heat castor sugar in another non-stick pan and cook till it caramelizes.
Add hot cream to chocolate and mix well till smooth.
Heat remaining cream in a non-stick pan and bring to boil. Add to caramel and mix well.
Add sprig bourbon vanilla extract. Transfer in a bowl and cool.
Add hazelnut-chocolate spread to chocolate-cream mixture and mix well.
Add some whipped cream and fold well.
Roughly chop 6-8 hazelnuts.
Fill in caramel mousse and chocolate-hazelnut mousse mixture in 2 different piping bags.
Place ring moulds onto a serving platter.
Place a sponge roundel in the mould, pipe out a thin layer of caramel mousse and tap.
Put some chopped hazelnuts, pipe out some chocolate mousse and level it out.
Refrigerate to set for 1-2 hours.
Melt the remaining dark chocolate in a microwave and mix well.
Take a projector sheet, pour some melted dark chocolate over and spread evenly and set aside.
Cut the set chocolate sheets into roundels using a medium cookie cutter.
Demould the mousse and place the chocolate disc.
Put the chocolate coated hazelnuts over the edge of the discs.
Serve.
