Using a hand mixer or a stand mixer fitted with the paddle attachment, cream the butter with the sugar and salt until smooth. Add the flour, cocoa powder, and hazelnut bakery emulsion and mix on low speed until combined. The cookie dough will be soft.

Transfer the dough onto a piece of parchment paper. Use your hands to form into a log shape, then roll the dough tightly in the parchment paper. Chill in the refrigerator for at least 2 hours.

Preheat the oven to 350? and line two baking sheets with parchment paper. Remove the cookie dough from the refrigerator, unwrap, and slice into rounds measuring about ½ inch thick. Arrange on the prepared baking sheets, about 2 inches apart. Bake for 18-20 minutes. Allow the cookies to cool on the baking sheets for 15 minutes, then transfer to a wire cooling rack to cool completely.