Puree the raspberries with the blender and then strain them through a sieve. Now put the raspberry pulp in a measuring cup and fill up to 500 ml with cream. Whisk some of it with the cornstarch so that it does not form lumps. Bring the rest of the raspberry cream with sugar and vanilla sugar to the boil. Take the pot off the stove and quickly stir in the mixed cornstarch. Put the pot back on the plate and let the pudding boil briefly, stirring constantly, until it hardens, which only takes a few seconds. Now you can, if you want, add a little raspberry syrup for the color.
Pour the pudding into portion bowls. Cover with cling film directly on the surface of the pudding so that no skin forms. Chill in the refrigerator for about 1 hour. The pudding is very easy to turn out.