Preheat your oven to 350°F (175°C) and grease an 8x8-inch baking pan or line it with parchment paper for easy removal.
In a large mixing bowl, combine the creamy peanut butter, cocoa powder, granulated sugar, brown sugar, eggs, vanilla extract, and salt. Mix until smooth and well combined.
If using, fold in the chocolate chips until evenly distributed throughout the batter.
Pour the brownie batter into the prepared baking pan and spread it evenly with a spatula.
Bake in the preheated oven for 20-25 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
Allow the brownies to cool in the pan for at least 10 minutes before transferring them to a wire rack to cool completely.
Once cooled, cut into squares and serve.