Prepare the mousse:pour the sugar into a heavy-bottomed saucepan. Add 10 cl of water and bring to the boil, boil for one minute.
Whip the egg whites until stiff. Pour the boiling syrup in a thin stream over the whites, continuing to whip until you get a smooth and shiny snow.
Soak the gelatin in a little cold water to soften it.
Wash*, dry and hull the strawberries. Reduce 700 g to a puree. Cut the rest in half lengthwise.
Drain the gelatin, melt it by incorporating it into the strawberry puree slightly warmed with the lemon juice.
Whip the cream.
Gently fold the purée into the mousse, then into the whipped cream. Book.
Prepare the syrup:put 10 cl of water in a saucepan and add the sugar (3 tbsp), bring to the boil and cook until the syrup thickens. Off the heat add the Grand Marnier.
Cut the sponge cake in the thickness in 3, then re-cut it into an oval, place the lower oval on a serving platter, soak it in syrup and coat with mousse , add here and there the half-strawberries, continue like this, ending with an oval of sponge cake to which you will give a domed shape with the cookie scraps. Reserve in the fridge for 3 hours.
Take out the cake and using a pastry bag, cover it with small domes of whipped cream. Roll out the marzipan and cut wide strips from it and tie a knot.
*wash strawberries with their stems on to avoid soaking them.
