How to make
Cool the crème fraîche in the refrigerator and wash and drain the raspberries in a colander. Soak the gelatin in the cold water. Cut the vanilla pod in half, scrape out the insides and put the seeds and pods in the milk that you've already put to heat on the stove. Add the sugar and a pinch of salt and bring the milk to a boil. Then remove the pods.
Beat the eggs and gradually pour the milk into them. Put the cream back on the stove and stir until it thickens but without letting it come to a boil. Drain the water from the gelatin and mix it into the warm cream so that it melts and let it cool completely. Put in the refrigerator to cool.
Smear the sides and bottom of a cake pan with removable sides with butter and sprinkle with sugar. Vertically arrange the biscotti along the sides, setting aside one of them.
Beat the crème fraîche, beat the egg cream and gradually mix them slowly until homogenized. Pour 1/3 of the mixture into the cake pan. Arrange a layer of raspberries, then a layer of cream, raspberries again and finish off with cream. Sprinkle with the set aside and crumbled biscotti, cover the cake with foil and leave in the fridge for at least 6 hours or overnight.
For the raspberry sauce, wash and drain the raspberries. Set aside 20 for decoration. Pass the rest through a sieve and mix the puree with the powdered sugar, lemon juice and raspberry liqueur. Beat the mixture with a hand blender or in a regular blender.
To take out the Charlotte from the cake pan, dip it for a few seconds in hot water, remove the sides and put the cake in a platter. Decorate with raspberries. Serve the raspberry Charlotte cut into pieces, with the fruit sauce poured on top of it.