Makes about 3 dozen cookies
I use Valrhona's Dutched cocoa. I think it's got the richest, most chocolaty flavor and color. The flavor of the cookie depends entirely on the quality of the cocoa here. They will not be the same amazing cookie is you use an inferior cocoa.
No hazelnuts? No hazelnut flour? No problem! Substitute almonds. Use regular flour. Just don't skimp on the cocoa.
2 cups all purpose flour (or one cup flour and one cup hazelnut flour)
3/4 cup cocoa powder
1 teaspoon baking soda
1/4 teaspoon salt
1 cup sugar
1 teaspoon vanilla extract
1 cup hazelnuts, toasted and coarsely-chopped
3/4 cup chocolate chips
Preheat oven to 350
Toast the hazelnuts for 5-7 minutes in the preheated oven. Cool. Rub together between your hands to remove skins.
Sift together the flour, cocoa powder, baking soda, and salt.
In a large mixing bowl, or the bowl of a stand mixer, beat the eggs, sugar and vanilla. If doing it by hand, whisk vigorously for a minute. On the stand mixer, use the paddle and beat for about a minute. Add the dry ingredients and mix until just combined. Then add the nuts and chocolate chips and mix gently until incorporated. The dough will be a little wet - this is ok.
Line a baking sheet with parchment paper or a silicone mat.
Lightly flour a work surface and divide the dough in half. Roll the dough into two logs - to about the length of the baking sheet. The logs should be about 2-3 inches wide. Transfer the logs onto the baking sheet, spaced evenly apart.
Gently flatten the tops of the logs and bake for 20-25 minutes, until the dough feels firm. Cracks in the dough are normal after the first baking.
Allow the logs to cool completely. Use a serrated bread knife to cut the cookies into 1/3-inch thick slices. Lay the cookies cut side down on baking sheets and return to the oven for another 20-25 minutes, turning the baking sheet or flipping cookies over midway during baking.
Once cool, store the cookies in an airtight container for up to two weeks. Serve with espresso or with ice cream.