preheat your oven to 180c/160c fan oven and line 2 baking sheets with parchment paper.
Add your butter, sugars and egg to the bowl of your mixer and mix until combined.
Sift in the flour, cocoa powder, bicarb and salt and mix into a dough.
Use a spoon to scoop out a small amount, roll into a ball and then press it slightly onto a baking sheet.
Repeat this 12 times until all the dough is used up. Put 6 cookies on each baking sheet.
Bake in the oven for 12-15 minutes. When they are ready leave them to cool for a couple of minutes then transfer to a cooling rack. Enjoy!