Preheat your oven to 350°F (175°C).

In a medium bowl, whisk together the all-purpose flour, baking soda, and salt until well combined.

In a large mixing bowl, cream together the unsalted butter, brown sugar, and granulated sugar using an electric mixer until light and fluffy.

Add the eggs and vanilla extract to the creamed mixture and mix until combined and smooth.

Gradually add the dry ingredient mixture into the wet mixture, mixing until just incorporated.

Scoop tablespoon-sized portions of the cookie dough, flatten each scoop slightly, place a small piece of brownie in the center, and fold the dough over the brownie.

Place the stuffed cookies onto the prepared baking sheet, spacing them about 2 inches apart.

Bake in the preheated oven for 12-15 minutes, or until the edges are golden and the centers are slightly underbaked.

Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.