In a large bowl, mix together the sugar, butter, vanilla, and cocoa. Then, beat in the eggs.
With the mixer on low speed, add in the sifted flour and salt. Mix until fully combined, scraping the sides down as needed. Pour the batter into the pan and spread evenly.
Scoop the peanut butter into a microwave safe bowl and heat for 15-20 sec or until warm. Drizzle the peanut butter over the batter, and use a spoon or small spatula to swirl it in without fully mixing.
Crush the Nutter Butter cookies into chunks and sprinkle evenly over the top of the batter. Bake for 20-25 minutes and let cool. Serve and enjoy!
Notes
Microwaving the peanut butter until warm provides a thinner consistency, making it easier to mix into the brownie batter.