Add 150 g butter and 60 g icing sugar to a mixing bowl, then whisk until smooth and well combined.

Add 180 g all-purpose flour and 20 g cocoa powder, then fold with a silicone spatula until a soft dough forms.

Add up to 22.5 ml milk a little at a time, then gently mix only until the dough comes together.

Roll the dough into a rough rectangle about 5 mm thick, then cut it into long narrow cookie sticks.

Arrange the cookie sticks on a parchment-lined baking tray, then refrigerate for 60 min until firm.

Bake the chilled cookie sticks at 180°C for 8-10 min, then remove them when their edges feel firm.

Transfer the baked cookie sticks to a wire rack, then cool them completely before decorating.

Melt 55 g dark chocolate and 55 g milk chocolate in a heatproof bowl, then dip one end of each cooled cookie stick into the melted chocolate.