Preparation Steps

• In a medium bowl, whisk together the flour, cocoa powder, baking soda, and salt. Set aside.
• In a large bowl, cream together the butter, granulated sugar, and brown sugar until light and fluffy. Beat in the vanilla extract.
• Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Stir in the chopped chocolate.
• Divide the dough in half and shape each half into a log about 1.5 inches in diameter. Wrap tightly in plastic wrap and chill for at least 2 hours, or overnight.
• Preheat oven to 325°F (160°C). Line baking sheets with parchment paper.
• Remove the dough from the refrigerator and slice into 0.5-inch thick rounds. Place cookies on the prepared baking sheets, leaving some space between each cookie.
• Bake for 10-12 minutes, or until the edges are set. Let cool on the baking sheets for a few minutes before transferring to a wire rack to cool completely.