Soak the gelatine until it has cooled down. Stir vanilla pulp, 50 g sugar, egg yolks and milk. Heat with the mixer on the lowest setting in the saucepan on 2 or automatic heat 3 to 4 until the cream thickens. Squeeze the gelatine, let it melt in the cream and set aside to cool.
Whip the cream with the vanilla sugar until stiff and fold in. Fill into ramekins, cool for 2 hours and turn out onto plates.
Boil 150 ml of water with cassis, juice of one lemon, zest and 50 g of sugar until syrupy on 3 or possibly on automatic heat 12. Add the blueberries and let them bubble up. Serve cold with the mousse.