The butter mix with both types of sugar with wire or spoon until fluffy cream. Add the egg and vanilla and again crashed. Add the flour and cocoa mixture and stir with a spoon - gets quite dry, but managed to wet the entire. Should be mixed to homogeneity. Finally, the chocolate was added and stirred gently until uniformly distributed. From the soft mixture with a tablespoon to scoop to form balls or slightly rolled biscuits. Arrange in a baking dish, covered with baking paper and bake in preheated oven to 160C (low moderate temperature). Bake 10-15 minutes, but must be removed while they are still soft because upon cooling harden. It is better to be hard on the outside and juicy inside. Remove and leave to cool on a grid. * Cool cookies are stored in a tightly closed box. * The number depends on the size, we went around 20. * 1 cup = 250 ml