Soak gelatine in cold water. Select the raspberries, wash and drain if necessary. Puree the raspberries with a hand blender, except for about 100 g for sprinkling. Pass through a fine sieve. Mix with mascarpone, crème fraîche, sugar, rose water and lemon juice.
Squeeze out the gelatine and dissolve in a small pot at very low heat. First stir 3 tbsp. raspberry cream into the gelatine, then stir everything into the rest of the cream. Chill for about 15 minutes until the cream begins to gel.
Whip cream until stiff, fold into the gelling cream. Cover and chill for at least 3 hours. Sprinkle mousse with the remaining raspberries.