1. Add the butter and sugar to a large bowl and mix until very light and fluffy. Add the eggs one after another and mix well after each addition. Next, add the vanilla extract and stir in. In a second bowl, mix flour with ground cinnamon, baking powder, and salt. Add to the large bowl and mix until just combined. Add the hazelnuts and fold in.

2. Line a baking sheet with baking parchment. Divide the dough into two portions and shape each one into a 25cm (10 inches) long log/roll with floured hands – place them on the prepared baking sheet with some space in between and place everything in the fridge for about 30 minutes.

3. Preheat the oven to 180°C (350°F). Brush the logs/rolls with egg white and bake them for about 30-32 minutes. The dough should have nicely browned and be no longer soft when you touch it (be careful, it’s hot). Take out of the oven and let cool down for about 10 minutes.

4. Use a very sharp knife or serrated knife to cut the slightly cooled logs diagonally into slices that are about 1 cm (0.4 inches) thick. Place the slices back on the baking sheet, this time the pieces can be placed close to each other, and then bake them again for about 12-15 minutes. You can also flip the Biscotti halfway through, so they are baked more evenly. Remove from the oven and them cool down on a wire rack.

5. If you want to decorate the Biscotti, melt the dark chocolate with the coconut oil. Let cool down for a moment, then brush the long, straight sides of the Biscotti with it and sprinkle with chopped hazelnuts. Let cool and dry completely, then store the Biscotti in a cookie tin in a cool, dry place.