Mix flour, sugar, drink powder and salt in a bowl. Add egg and butter in pieces. Knead first with the dough hooks of the hand mixer, then with your hands to a smooth dough. Wrap the dough in foil and chill for approx. 45 minutes
Roll out half of the dough on a floured work surface 2-3 mm thin to form a rectangle (25 x 35 cm). Cut the rectangle lengthwise into 5 strips (approx. 5 cm each). Cut each strip of dough into 5 pieces (à 5 x 7 cm)
Cut out 1 small hole in the middle of each narrow side with a small hole punch. Fold both corners of the narrow side towards the middle and press them down, leaving the hole free. Process the rest of the dough in the same way
Place the biscuits on 2 baking trays lined with baking paper. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) one after the other for approx. 12 minutes. Remove the cookies and let them cool down on a cake rack
Chop the chocolate coating and melt it over a warm water bath. Dip the biscuits with the side without a hole halfway into the couverture, sprinkle the couverture with sugar pearls and leave to dry in a cool place
waiting time approx. 2 hours