2 1/4 cups unbleached all-purpose flour (I like to replace 1/4 cup to 1/2 cup whole wheat flour for the all purpose)
1/4 cup dutch-processed cocoa powder
1 tsp baking soda
1 1/2 cups granulated sugar, 1 tsp granulated sugar for glaze (I used 1 cup and it's the right sweetness for me)
1 tsp kosher salt
1 1/2 cups(about 8 ounces) blanched hazelnuts
12 oz semisweet or bittersweet chocolate chunk(I like to use one pack of 3.5oz 72% Lindt and make up the rest with Nestle Tollhouse Chocolate chips)
4 large eggs, at room temperature
1 eggwhite for glaze (optional), at room temperature
Sanding sugar (or granulated)for sprinkling (optional)
Preheat oven to 350F.Line two large baking sheet with parchment paper. Set aside.
In a food processor, pulse the flour, cocoa,baking soda,salt, 1 cup of chocolate chunks and hazelnut, until chocolate chunks and hazelnuts are the size of peas. *if you don't have a food processor, coarsely chop the nuts and chocolate and sieve the flour.
In a bowl of electric mixer fitted with whisk attachment, beat the whole eggs, and granulated sugar until the mixture holds a ribbon-like trail on the surface for a few seconds when you raise the whisk.
Switch to the paddle attachment. With mixer on low speed, add the flour mixture. When it's well combined, add in the nuts and chocolate and stir by hand, using a large spatula.
Turn out dough onto a lightly floured work surface, and divide into 3 equal pieces. Shape each pieces into an 18 inch log. Transfer to prepared baking sheet. With the palm of your hand, gently press the logs to flatten slighlt. Brush egg wash over logs. Sprinkle with sanding sugar if using.