Instructions

To make the cookie dough

1. Place the butter, sugars and vanilla into the bowl of a stand mixer.
2. Using the flat-paddle attachment, cream the butter and sugars for about 5 minutes on medium speed, or until the mixture is light and fluffy.
3. On low speed, add the flour, one tablespoon at a time.
4. Once the flour is almost all incorporated, add the chopped chocolate.
5. Lightly beat the chocolate into the dough so that it is evenly distributed. This should take a few rotations of the stand mixer.

To shape the cookie dough

1. Place a large sheet of plastic wrap on the kitchen bench.
2. Using your hands or a bench scraper, scoop some dough onto the plastic wrap, and continue until you have enough for a long log which is roughly 4-5 cm (1.5-2 inches) in diameter (or however big you like your cookies).
3. Lightly shape the dough into a long log, although it doesn’t need to be perfect at this stage. 
4. Tightly wrap the dough in the plastic wrap, forming a smooth log as you do so.
5. Squeeze and secure the ends.
6. Repeat the above steps with the remaining dough. 
7. Place the logs of dough in the fridge for at least 1 hour to firm up, or you can store them in the freezer to bake another time.

To decorate the cookies

1. Line a large sheet pan with baking paper.
2. Unwrap the cookie dough log and leave it to rest on the plastic wrap.
3. Using a brush to lightly brush the cookie dough with egg wash.
4. Place a generous amount of demerera sugar on a baking sheet or plate which is big enough to hold the cookie dough log.
5. Roll the cookie dough in the sugar until it is evenly coated.
6. Using a sharp knife, slice the cookies from the log, about 1 cm (1/2 inch) thick.
7. Occasionally, your knife will hit a piece of chocolate, making it difficult to slice neat rounds. If your cookie slices fall apart, simply squish them back into shape.
8. Place the cookies on the sheet pan, spaced about 2 cm (1 inch) apart.

To bake the cookies

1. Preheat the oven to 180°C (350°F) (without fan).
2. Bake the cookies for 12 to 15 minutes, or until the edges are golden and caramelised, and the cookies or lightly golden on top.
3. Leave the cookies on the hot sheet pan for 5-10 minutes before removing them to a wire rack to cool completely.