Ingredients

1¾ cups all-purpose flour
⅔ cup Dutch process cocoa powder
½ tsp baking powder
½ tsp salt
1 cup granulated sugar
1 cup packed (25g) fresh mint leaves, washed and dried
¾ cup unsalted butter, softened
1 large egg
1 tsp vanilla extract
coarse sanding sugar or granulated sugar for rolling 

Method

In a medium bowl, sift together the flour, cocoa powder, baking powder and salt. Set aside. Add the granulated sugar and mint leaves to a food processor and blend until the mint is finely chopped and the sugar turns a green hue.

In a large bowl, beat together the butter and mint sugar until light and fluffy. Beat in the egg and vanilla extract until combined. Add the flour mixture to the butter mixture and beat on low speed until the dough comes together and no flour streaks remain.

Turn out the dough onto a large piece of parchment paper. Using your hands, shape and roll the dough into a smooth cylinder approximately 2 inches in diameter and 14 inches long. Roll the dough tightly in the parchment, making sure to maintain the shape, then twist the ends like a candy wrapper. Place in the fridge for minimum 2 hours or overnight.

After the dough has chilled, preheat the oven to 350°F and line a large baking sheet with parchment paper. Set aside.

On a large cutting board, unwrap the dough and sprinkle the sanding sugar on the parchment wrapper, then roll the dough in the sugar to coat evenly. Slice the dough into rounds a little wider than ¼ inch. Place the rounds on the prepared baking tray about one inch apart. Gently reshape any rounds if needed. 

Bake in the preheated oven for 12–14 minutes or until the centres have some resistance when lightly pressed. Remove from the oven and transfer to a wire rack to cool completely.

Notes

If fresh mint is not available, use ½ tsp of peppermint extract and add it along with the egg and vanilla.