1. Place oven rack in the center and preheat oven to 350°F (175°C). Line a large baking sheet with a silicone baking mat (I love this silpat) or parchment paper. 
2. In a large mixing bowl, whisk together the flour, baking powder, and sea salt. Set aside.
3. In a large bowl of an electric mixer fitted with flat beater attachment, cream the butter and sugar until fluffy and light, about 1-2 minutes. Scrape down the sides of the bowl with a spatula, as needed. Alternatively, you can mix the butter and sugar by hand using a spatula and fork (you will need to make sure butter is softened). Carefully beat in the eggs, on low speed, one at a time. Add vanilla extract.
4. Add dry ingredients to the egg mixture, slowly, a little at a time, on low speed, until just incorporated. Do not over-mix. With a spatula or danish whisk, fold in the chocolate chips and most of the chopped hazelnuts (reserve a handful for sprinkling at the end).
5. Using a spatula, turn dough out onto a floured surface. Using well-floured hands, shape into a rough ball, then press down into a disc. Work quickly and don’t overwork the dough. Cut the dough in half with a bench scraper or large sharp knife.
6. Shape each half into a short log, rolling it back and forth with floured hands. Move each piece of dough to the lined baking sheet, leaving enough space between them to allow them to spread. Shape each into a longer log shape, pressing down slightly to form logs 2 inches wide and 2/3 inch tall.
7. Bake for approximately 30 minutes or until firm to the touch. Take out and let cool slightly, for about 10 minutes.
8. Move logs to a cutting board and, using a sharp serrated knife, slice at an angle to form 3/4 inch thick biscotti.
9. Turn the biscotti on their side so that they lay flat with the cut sides facing up, and arrange them evenly on the baking sheet. Bake for about 10 more minutes, until they become slightly firm. They will firm up more as they cool and become delightfully crisp.
10. Remove from oven and allow to rest 5 minutes on the baking sheet before moving to a cooling rack. Let cool completely before dipping into chocolate.

Melted Chocolate to Dip

1. Place the chocolate in a medium microwave-safe bowl and microwave in 15 seconds increments, stirring vigorously between sessions, until all melted.
2. Dip each biscotti in the chocolate and sprinkle with the remaining chopped hazelnuts. Place on the cooling rack and allow chocolate to set. Placing them in the fridge will help them set faster. Enjoy with tea or coffee!