For the chocolate mousse the day before, line a box mould (25 cm long; 1.5 l capacity) with foil. Soak 2 sheets of gelatine in cold water. Heat milk and 2 tablespoons of sugar. Remove the pot from the stove.
Divide 300 g chocolate into pieces and melt in the hot milk. Squeeze the gelatine and dissolve in the hot chocolate milk. Pour into a bowl and let it cool down for about 30 minutes.
Whip 500 g cream until stiff, then add cocoa. Fold 2 portions of cream into the chocolate. Spread the mousse into the cake tin. Chill overnight.
The next day, turn the mousse onto a plate, remove the foil. Cut a carrot-shaped wedge from the mousse along the entire length, except for 1 cm at each end (use the cut-out mousse for other purposes).
Chill the mousse again.
For the orange mousse, soak 2 sheets of gelatine. Mix crème fraîche, 2 tablespoons sugar, orange peel and orange juice. Add red and yellow food colouring to a strong orange colour. Beat 100 g cream until stiff.
Squeeze the gelatine, dissolve carefully. Stir 2 tablespoons of cream into the gelatine, then stir everything into the remaining cream. Fold in the cream. Pour orange mousse into a piping bag and squirt into the wedge-shaped recess.
Carefully tap the plate several times onto the work surface so that the mousse is well distributed. Chill the mousse for another 2 hours.
Coarsely chop 100 g chocolate and cake glaze and melt in a hot water bath, let cool a little. Carefully cover the mousse with the chocolate icing. Keep cold until the chocolate has solidified.
For the green, knead marzipan with icing sugar and green food coloring. Form approx. 8 cones, cut in the tip approx. 3 times with scissors. Straighten the lower end. Decorate the mousse with it.