Preheat the oven to gas mark 4, 10 minutes before baking.
Make the chocolate filling by breaking the chocolate into small pieces and placing into a heatproof bowl.
Put the double cream into a saucepan and heat to boiling point. Immediately pour over the chocolate. Leave stand for 1-2 minutes, then stir until smooth. Set aside to cool until firm enough to scoop. DO NOT REFRIGERATE.
Lightly oil a baking sheet. Cream together the butter and the sugar until light and fluffy.
Blend in the peanut butter, followed by the golden syrup and milk.
Sift together the flour and bicarbonate of soda. Add to the peanut butter mixture , mix well and knead until smooth.
Flatten 1-2 tablespoons of the cookie mixture on a chopping board. Put a spoonful of the chocolate mixture in the middle into the centre of the cookie dough, then fold the dough around the chocolate to enclose completely.
Put the balls on the baking sheet and flatten slightly. Bake in preheated oven for 10-12 minutes until golden. Remove from the oven and transfer to a wire rack to cool completely and serve.