Preheat Oven and Prepare Baking Sheet: Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone mat.
Combine Dry Ingredients: In a large mixing bowl, whisk together almond flour, erythritol, cocoa powder, baking powder, and salt. Stir in the chopped hazelnuts.
Mix Wet Ingredients: In a separate bowl, beat the eggs, then mix in the melted butter and vanilla extract until well combined.
Combine Wet and Dry Ingredients: Pour the wet ingredients into the dry ingredients and mix until a dough forms.
Shape the Biscotti: Divide the dough into two equal parts. On the prepared baking sheet, form each half into a log approximately 1/2 inch thick, 2 inches wide, and 8 inches long.
First Bake: Place the baking sheet in the oven and bake for 25 minutes, or until the logs are set and a toothpick comes out clean.
Cool and Slice: Allow the logs to cool for 15 minutes, then slice diagonally into 1/2 inch thick slices using a serrated knife.
Second Bake for Crispness: Lay the slices cut-side down on the baking sheet and bake for another 10-20 minutes, flipping halfway through, until they reach your desired crispness.
Melt Chocolate: While the biscotti are cooling, melt the sugar-free dark chocolate chips in a microwave-safe bowl in 30-second intervals, stirring between each until smooth.
Dip Biscotti in Chocolate: Dip one end of each biscotti into the melted chocolate and lay them back on the parchment paper to set.
Cool Completely: Let the biscotti cool until the chocolate is firm to the touch.