Preheat the oven to 180 C / Gas 4. Line a baking tray with baking parchment.
Cream together the butter and both sugars. Beat in the egg and vanilla extract until well combined. Sift in the flour, cocoa powder, and salt, and beat once more. Stir in the chocolate chips until evenly distributed. Spoon the mixture in tablespoons onto the prepared baking tray, allowing room to spread out.
Bake for 8 to 10 minutes until golden brown. Remove from the oven and transfer to a cooling rack. Enjoy!