Preheat the oven to 170 degrees Celsius/ 340 degrees Fahrenheit. Butter a loaf pan of about 30 cm/ 12 inches.

Grate the dark chocolate on a fine grater or process the chocolate in the food processor, it should be rather finely ground. If using dark chocolate chips you will not be able to grate them, but then you will definitely need a food processor to grind them finely.

Mix the dried breadcrumbs, sugar, grated chocolate, ground hazelnuts, baking powder, and salt in a bowl. Stir to combine.

Add the soft butter and the eggs. Mix slowly with the hand-held mixer for 30 seconds, then increase the speed and mix for another 30 seconds.

Pour the batter into the prepared loaf pan and bake for 60 to 70 minutes, depending on your oven. Turn off the heat and let the cake stand for another 5 to 10 minutes in the hot oven. Remove from the oven.

Let stand in the pan for about 20 minutes, remove and let cool completely on a wire rack. Sprinkle with icing sugar before serving.