Miso chocolate cookies

Beat the butter and sugars together in a bowl until well-combined. Whisk in the egg, followed by the miso and vanilla. Fold in the flour, cocoa, baking powder and salt until the mixture is uniform in colour, then fold in the chocolate chips. The dough will be fairly stiff, so you may need an electric whisk to help mix in all the flour.

Tip the dough out onto the middle of a large sheet of baking paper and roll into a rough log shape. Roll up in the paper, moulding the dough into a 7cm-thick sausage as you go. Twist both ends and chill for 2 hours until firm, or for up to a week. The dough can also be frozen at this stage for up to a month.

Heat the oven to 190C/fan 170C/gas 5 and line two baking sheets with baking paper or silicone baking mats. Cut the dough log into 1cm-thick cookies and arrange them on the prepared baking sheets, well spaced apart to leave room for spreading. Sprinkle a tiny pinch of sea salt flakes or sesame seeds over the cookies or leave them plain if you prefer.

Bake for 13-15 minutes or until the edges are crisp and the middles are still slightly soft. Leave to cool for 5-10 minutes on the sheets or until firm enough to pick up, then transfer to a wire rack to cool completely. Keep in an airtight container for up to a week.