Pour the chocolate mousse into a 500 ml siphon and aerate with one gas cartridge. Store in the refrigerator.
For the cherry jelly, heat the cherry purée with the agar agar and simmer for a few minutes. Add the gold dust and pour into cherry moulds.
For the coulis, heat all the ingredients together and pass through a fine sieve. Allow to cool, then transfer to a siphon.
Cut the chocolate brownie into 10 equal pieces.
Pour the cherries into a sieve and save the juice. Heat the juice with the cinnamon and star anise and reduce to a third. Add the cherries again and marinate in the juice.