After-dinner mint biscuits

1.Process flour, icing sugar, cocoa and a large pinch of sea salt in a food processor to combine, then add butter and pulse until mixture is sand-textured. Add yolk and process until mixture comes together. Turn out onto a work surface and gently knead to come together. Form into a rough cylinder and roll until smooth and 5cm in diameter. Wrap in plastic wrap and refrigerate until chilled and firm (1 hour).

2.Preheat oven to 180C. Unwrap dough and cut into 5mm-thick slices. Place on 2 oven trays lined with baking paper (leaving about 3cm between each biscuit) and bake until biscuit edges are firm (10-12 minutes; swap trays halfway through cooking). Cool slightly on trays, then transfer to a wire rack to cool completely.

3.For peppermint filling, place chocolate in a bowl and set aside. Bring cream to the simmer in a small saucepan over medium heat. Pour over chocolate, set aside to melt chocolate (5 minutes), then stir until smooth. Add peppermint extract, set aside to cool to spreading consistency, then stir in crushed peppermint. Spoon a little of the peppermint filling onto half the biscuits, sandwich with remaining biscuits, set aside to set (15 minutes) and serve. Biscuits will keep stored in an airtight container for 3 days.