Step 1

Beat together the cocoa powder and the softened butter to create a thick paste. Beat in the sugar, followed by the egg and the vanilla extract.

Step 2

Once the mixture is smooth and glossy, stir in the flour and baking powder until just combined. Chill for 1 hour.

Step 3

Preheat the oven to 340F and line two trays with baking parchment.

Step 4

Roll the dough into scant tablespoon sized balls, then roll them in the powdered sugar, shaking off any excess.

Step 5

Space the cookies at least 1 1/2 inches apart on the prepared trays and bake for 12 minutes until puffed and crackled.

Step 6

Leave to cool on the trays before transferring the cookies to an airtight container where they’re best eaten within 3 days.