Put the bananas, 200g sugar and 150ml water in a pot and mix together. Then let it simmer to make a thick mixture. Then let it cool and blend it to make a banana puree. In another pot put all the ingredients of the syrup and boil for 5 minutes. Let it cool and add 2 shots of vermouth. Mix together 15g of gelatine with 50ml of water and melt for 20 seconds in a microwave. Whip 500ml cream to a ribbon stage, add ¾ of the banana puree and the gelatine mixture and mix together. To assemble the mousse, cut the sponge into layers and place one of them in a ring. Pour some syrup on the sponge, than put some of the cream mixture on the sponge and spread it throughout the ring. Put another sponge on top and then repeat the process. Smooth the edges of the mould with the cream. Freeze for 1 hour and then add the remaining banana puree on top. Then un-mould the mousse and garnish to your desire .