Preheat your oven to 375°F and adjust the racks to the middle and upper thirds. Prepare two baking sheets by lining them with parchment paper for easy cleanup and even baking.

In a large mixing bowl, combine the flour, baking soda, and salt. Pass the cocoa powder through a fine-mesh sieve to eliminate any lumps, then whisk everything together until well-blended.

Using an electric mixer, beat the softened butter with the brown sugar, granulated sugar, and vanilla extract until the mixture is creamy and smooth, about one minute. Crack in the eggs, one at a time, and beat on medium speed for approximately two minutes, or until the mixture is light and airy.

Gradually incorporate the dry ingredients into the butter mixture on low speed. The dough may initially appear crumbly but will come together as you continue mixing. Once fully combined, fold in the chocolate chips and chopped pecans using a spatula or the mixer on low speed.

Chill the cookie dough in the refrigerator for about 30 minutes, allowing it to firm up for easier handling. Roll the chilled dough into balls roughly the size of a tablespoon, spacing them about 2 inches apart on the prepared baking sheets.

Bake the cookies for 8 to 10 minutes, or until they appear puffed and slightly set around the edges. Allow the cookies to cool on the baking sheets for 2 minutes before transferring them to a wire rack to cool completely. Repeat the process with any remaining dough.

Store the cookies in an airtight container to maintain freshness for up to three days. Enjoy their rich, chocolatey flavor with every bite!