Place flour, nuts, sugar, vanilla sugar, 2 teaspoons cocoa, 1 pinch of salt, egg yolk, espresso and butter in flakes in a mixing bowl and knead into a smooth dough using the dough hooks of the mixer.
Divide the dough into eighths and form each into a roll (approx. 42 cm long). Wrap in foil and chill for about 1 hour.
Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: level 3). Line three baking trays with baking paper. Cut each roll into about 7 sticks and place them on the trays. Bake in the oven for 11-13 minutes one after the other.
Let it cool down.
Chop the couverture and melt in a hot water bath. Dip the ends of the mocha sticks into the couverture and allow to dry. Sprinkle with 1/2 teaspoon of cocoa.