Preheat the oven to 350˚f (180°c) and line a baking tray with grease proof paper.

In a heatproof bowl melt the chocolate and butter in a double boiler over simmering water. (or you can melt the chocolate in a microwave stirring the mixture every 30 seconds). Once the chocolate completely melts let it cool for a little, about 5 minutes.

In a large bowl, whisk together the white and brown sugar, the egg and vanilla essence until the mixture is creamy.

Next, whisk in the chocolate-butter mixture.

Then sift in the flour, cocoa powder, and salt. Fold them into the mixture.

Scoop small ball-size dollops of cookie dough onto the baking tray using an ice cream scooper and a spoon, making sure you leave enough room for them to spread out. (don't make them too big otherwise, they spread out huge and become thin)

Bake for 10-12 minutes, until crispy and crackly on top and slightly gooey in the middle.

Let them cool to room temperature and enjoy!