113g unsalted butter, at room temperature
120g granulated sugar
172g Nutella, at room temperature
3 large eggs, at room temperature
2 tsp vanilla extract
390g all purpose flour
1/2 tsp baking powder
1/4 tsp salt
75g hazelnuts/almonds, skinned, toasted & roughly chopped
Preheat oven to 350˚F and position rack in the centre of the oven
In the bowl of a stand mixer fitted with a paddle attachment (or in a medium bowl with a handheld mixer), cream together the butter and sugar until light and fluffy. Add the Nutella and mix until fully combined. With the mixer on medium-low speed, add the eggs, one at a time, until well blended, scraping down the sides of the bowl after each addition.
In a medium bowl, whisk together flour, baking powder and salt. Add the dry ingredients to the wet mixture all at once, and mix on low speed until there are no more patches of flour visible. Add the chopped hazelnuts and chocolate, and mix on low until incorporated. Remove the bowl from the mixer and mix the dough by hand, using a rubber spatula, to evenly distribute the nuts and chocolate.
Divide the dough in half, and turn out onto a lightly floured surface. Gently squeeze and roll the dough into a log about 13 inches long. Transfer to a parchment lined cookie sheet, and gently press down and flatten the rolls until they are about 2 inches across on the top. Repeat with the second half of the dough, allowing 4 inches of space between the logs.
Bake for 30-35 minutes, until the logs are firm to the touch and lightly golden brown.
Transfer logs to a cooling rack and allow to cool completely (if you slice the cookies while they are still warm, the chocolate will smear and you'll have ugly biscotti).
Reduce oven temperature to 275˚F, and position 2 racks in the oven, dividing the oven into thirds.
Once the logs have completely cooled, using a sharp, serrated knife, slice the logs on a slight diagonal into individual cookies about 3/8 thick (I sliced mine much thicker). Place the sliced biscotti, cut side down, onto two parchment lined cookie sheets and place them back in the oven for another 30-40 minutes, rotating the cookie sheets about halfway through. The biscotti should be dry and lightly golden brown.
Transfer to a cooling rack and allow to cool completely.
These cookies will keep in an airtight container, at room temperature, for up to 2 months… that's assuming they don't all get eaten right away.