Break the chocolate into pieces and melt over a warm water bath. Remove the pot from the stove and let it cool down. Put butter in flakes and sugar in a bowl and stir until creamy with the whisk of the hand mixer. Stir in the eggs one by one. Fold in first the flour and then the melted chocolate
Grease a pudding mould (1 litre capacity) and pour in the dough. Cover with a layer of baking paper and wrap in aluminium foil. Tie the foil well. Place in a pot and pour boiling water into the pot so that it reaches half of the pudding mould. Cover and simmer for approx. 1 1/2 hours until the surface of the pudding is firm enough that no more dent can be made by finger pressure.
For the syrup, wash and clean the berries. Simmer the muscovado sugar and orange juice in a small pot at low heat for 4-6 minutes. Stir port wine and starch until smooth. Stir the starch into the syrup, bring to the boil and simmer for about 1 minute while stirring. Mix in the berries and take off
Turn the chocolate pudding onto a warm plate and pour the berry syrup over it