First, preheat the oven to 350°F. Line a 9x9 square baking pan with parchment paper.
Next, combine softened butter with sugar. Using your whisk attachment on the electric mixer, beat on medium speed for at least 2 minutes. Then, beat in the eggs and vanilla extract until combined. As needed, use a spatula to scrape the sides of the bowl.
Then, add flour, baking soda, salt, and cocoa powder to the batter. Mix until combined.
Next, fold in the chocolate chips and spread the batter into the prepared pan. Note the brownie batter will be thick. Bake at 350°F for 25-30 minutes (I start checking mine at 20 minutes).