Mix 175 g flour, icing sugar and salt. Add the egg and butter in pieces and knead to a smooth shortcrust pastry. Cover and chill for about 30 minutes.
Line 2 baking trays with baking paper. Roll out the short pastry to a rectangle (20 x 25 cm) on some flour 3 mm thick. Cut into about 50 sticks (1.5 x 6 cm) (first cut 20 strips of 1.5 cm width, then cut into 6 cm long sticks).
Place the sticks on the baking trays. Bake in the preheated oven (electric oven: 175 °C/circulating air: 150 °C/gas: level 2) for 10-12 minutes. Let them cool down.
Meanwhile roast the hazelnuts in a pan without fat, take them out. Put the nougat in the plastic package into a hot water bath and heat it up briefly. Then put it into a bowl and stir until creamy. Pour into a piping bag with perforated spout and immediately squirt a strand of nougat onto each stick.
Place 4 nuts on each. Chill for about 1 hour.
Chop the couverture and melt in a hot water bath. Dip the nut bars completely or only half into it. Drain well and dry on a cake rack or baking paper.