Place the flour, cocoa powder, baking soda and salt together into a medium bowl and whisk to combine, set aside until needed.
Place the butter and sugars into a large bowl and beat together until light and creamy, remember you are not making a cake so it doesn’t need to be fluffy just well combined and light and creamy.
Add the flour mixture and with the mixer on low speed mix together until the mixture is sandy. Sable is French for sandy and describes both the texture of the final cookie and this stage of the baking process. If you mix until you have a uniform dough the texture of the final cookie will be a bit tougher and they wont melt in the mouth. Add the chocolate and mix to combine. Tip the mixture onto the work surface and very gently knead to bring together. Divide the dough in half and roll into logs, about 4cm inches in diameter. Wrap in clingfilm and refrigerate. At this point I will normally freeze half of the dough ready to make cookies when emergency cookies are needed (happens more than you would expect!). Chill the dough for a few hours until firm.
Preheat the oven to 180°C/160°C Fan and line two baking trays with parchment paper. Using a thin sharp knife cut the log into cookies, about 1cm thick but don’t worry if the cookies crumble just press them gently back together. Place onto the prepared baking trays and bake for 10-12 minutes or until spread and lightly set around the edges but still looks undercooked in the middle. Allow to cool on the tray for 10 minutes before transferring to a wire rack to cool completely. Stored in a sealed container these cookies will keep perfectly for a few days.
Recipe courtesy of Edd Kimber.