Whisk together the eggs and sugar. Add half a cup of the milk and the melted butter to the eggs and stir through. Sift in the flour, baking powder, salt, mixed spice and cinnamon. Gradually add the remainder of the milk and stir/whisk lightly with a balloon whisk to incorporate everything.
Spoon out half a cup of the batter. Stir the cocoa into this half cup of batter along with one tablespoon of water to thin it a bit. Pour this chocolate batter into a squeeze-bottle. Drop spoonfuls of the spiced batter in a warm pan lightly coated with oil or butter. Once small holes appear in the surface of the crumpets, form a cross with the chocolate batter and immediately flip them to cook on the cross side as well. (If you draw the cross earlier, its edges will start to bleed and you won’t get as crisp a cross.) Serve warm with butter and golden syrup.