Put 100g of the blackberries in a blender and puree finely. Then spread the puree with a spatula, through a hair sieve, into a bowl.
In a mixing bowl, whip the cream with the cream stiffener until stiff. Stir in the powdered sugar, 2-3 tablespoons of liqueur and the vanilla extract. Here you can use more or less powdered sugar as you wish.
Fold the blackberry puree and the remaining blackberries into the cream with a spatula.
Then pour into prepared bowls or dessert glasses. If you like, decorate with a whipped cream and a blackberry.