Caramelise the sugar in a pan until golden. Add walnuts and turn in the caramel. Spread on a piece of foil lightly coated with oil and allow to set.
Clean and wash the chicory and rocket and drain well in a sieve. Wash and clean the pears and cut them into slices. Sprinkle with lemon juice. Coarsely chop the walnut caramel.
Put in a cool place for about 2 hours. Whip the cream until stiff. Gradually add the sugar. Remove the cake from the edge of the springform pan. Dust the surface evenly with cocoa. Pour the cream into a piping bag with a star-shaped spout and decorate the cake with cream tuffs.
Sprinkle with walnuts.