Finely puree the washed and cleaned strawberries with the hand blender. Put in a saucepan and mix with the preserving sugar. Bring the strawberry mixture to the boil and let it simmer for about 3-4 minutes.
In the meantime, grate the block chocolate finely and set aside.
Make a gelling test of the strawberry mass. When this is good, remove the pot from the hob and stir approx. 2 - 3 shot glasses full of sherry into the jam.
Carefully stir the grated chocolate into the jam and immediately pour into prepared glasses. Turn the glasses upside down for about 5 minutes.
Note: Since the chocolate is melting, it is not so easy to see. But when the jam has cooled, it gets little white chocolate stains.