Preheat your oven to 350°F (175°C) and prepare your baking sheets by lining them with parchment paper for easy cookie removal.
In a spacious mixing bowl, use an electric mixer to cream together the softened butter, packed brown sugar, and granulated sugar until the mixture is light and fluffy, which should take about 3-4 minutes.
Add the eggs to the bowl one at a time, mixing well after each addition to ensure a smooth batter. Pour in the vanilla extract and combine thoroughly.
In a separate bowl, whisk together the all-purpose flour, unsweetened cocoa powder, baking soda, and sea salt until they are well blended and free of lumps.
Gradually incorporate the dry ingredients into the wet mixture, stirring gently until the ingredients are just combined—be careful not to overmix to preserve the chewy texture.
Carefully fold in the chocolate chips and chopped walnuts (if you’re including them), making sure they are evenly distributed throughout the cookie dough.
Using a tablespoon or a cookie scoop, drop generous scoops of cookie dough onto your prepared baking sheets, ensuring there is ample space between each cookie because they will spread during baking.
Bake in the preheated oven for 10-12 minutes, keeping an eye on the cookies. The edges should be set, while the centers should still look slightly underbaked for that perfect chewy texture.
Once baked, remove the cookies from the oven and let them cool on the baking sheets for about 5 minutes. Then, carefully transfer them to a wire rack to cool completely.
Notes
For a delightful presentation, stack a few cookies on a cake stand or serve on a rustic wooden platter. Consider drizzling melted chocolate on top, or dusting with powdered sugar for an elegant touch!