Cream icing sugar and butter in pieces with the whisk of the hand mixer. Stir in milk, egg, vanilla sugar, speculoos spice and salt one after the other. Knead in flour
Pour the dough into a piping bag with a star-shaped spout (10 mm Ø) and distribute it in 4-5 cm long S-shaped forms on 2-3 baking trays lined with baking paper. Bake one after the other in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 15 minutes. Take out the biscuits and let them cool on the baking tray
Chop the couverture and melt it with coconut oil over a warm water bath. Dip about 1/3 of each biscuit in chocolate coating and decorate with pistachios. Allow to dry
Waiting time approx. 1 hour