In a saucepan, over medium heat, add the butter, granulated sugar, and light brown sugar. Stir until the butter is all melted and combined with the sugars.
Set aside to cool for 4 to 5 minutes. In a large mixing bowl, mix the flour, cacao powder, salt, and chocolate chips. Mix until all ingredients are combined.
To the butter-sugar mixture, once it has cooled, add the vanilla extract and the eggs one at a time. Mix well in between each. Pour the butter-sugar mixture over the flour mixture.
In a medium size bowl, mix the peanut butter, melted butter, powdered sugar, and vanilla extract. Mix until all are combined. Using a spoon, scoop the peanut butter onto the brownies.