Preheat the oven to 350 F or 180 C and line a cookie tray with parchment paper.

Melt the dark chocolate. You can do this over a double boiler or by microwaving the chocolate in a heat-proof bowl, stirring every 30 seconds for around 2 minutes or until smooth. Set the chocolate aside to cool slightly.

In a large bowl, beat together the butter and sugar until creamy.

Gradually stir in the melted chocolate, making sure that the chocolate has cooled to room temperature so that it doesn't affect the consistency of the butter and sugar mixture.

Beat in the egg and vanilla. At this stage, you might also choose to add in 1 tbsp of orange zest or 1 tsp instant espresso powder for extra flavoring.

Next, in a small bowl, combine the flour, cocoa powder, baking soda and salt, stirring till well-blended.

Add the flour mixture to the butter-chocolate mixture, until your result is a thick, sticky mass.

Now you can fold in the chocolate bits. You could also add in nuts if you would like.

Using an ice-cream scoop or a 1/4 cup measure, scoop mounds of the dough onto the prepared tray, about 3 inches apart.

Bake for 15-20 min or until the cookies have spread and cracked slightly. If you insert a toothpick in the 'cakey' part (careful not to pierce a chocolate chip), it should come out clean.

Cool the cookies completely before serving, as they are quite fragile. These are a great accompaniment to a glass of cold milk.