Pour a little water over the gelatin and leave it to swell.
In the meantime, whip the cream with the sugar and lemon sugar to a fluffy cream.
Crumble the biscuits and chop the fruits into pieces. Heat the gelatin to liquefy it (without boiling), then once cooled a bit, pour it in a thin trickle to the mixture while stirring nonstop, add the cut fruits and stir carefully.
Cover the insides of a bowl or cake form with plastic wrap, pour the mixture into it, press lightly with a spatula and even it out.
Put the form in the fridge for 3 hours until the gelatin hardens. Invert the form onto a platter and remove the form, along with the plastic wrap, serve.