Preheat the oven to 180°C (Electric oven | Electric fan oven 160°C | Gas Mark 4) and place the paper cases into a muffin tin.
Place the butter and sugar in a large bowl and whisk until light and fluffy. Gradually beat in the eggs.
Fold in the flour, cocoa powder, chocolate chips and milk. You should have a cupcake mixture with a dropping consistency - if not add a little more milk to thin the mixture.
Drop the chocolate chip cupcake mixture into the paper cases and bake in the oven for about 25 minutes or until a cake tester comes out dry at which point the cupcakes are done. Lift the chocolate chip cupcakes out of the muffin tin and leave to cool on a wire rack.