Preheat the oven to 350°F (180°C). Cover a 13x9-inch baking pan with parchment paper. If there is excess just let it sit over the sides of the pan.
In a pan over medium hear melt the butter with the chocolate chips and mix to form a paste
Add the cocoa powder and mix until combined. Set aside and allow it to cool.
Whisk in the sugar until combined.
Whisk in the eggs until combined.
Then, whisk in the sourdough discards, flour, salt and vanilla.
Spread batter into prepared pan, at this moment you can add more chocolate chips or any berry (I added blueberries!)
Bake for 25-30 minutes until depending on how fudgy and moist you like it.
Let the brownie cool completely in the pan. Cut into squares and enjoy!