Pre-heat oven to 200 degrees Celsius. Mix together butter and sugar. Add eggs. Gradually add flour. If mixture looks dry, add dash of milk.
Break up all chocolate into chunks and with hands, mix into mixture, spreading chunks evenly throughout. Part mixture into even balls (sized as half tennis balls) and put on tray with grease-proof paper.
Place in oven for 10 minuets. Take out and leave to cool for 20-30 minuets.