Prepare

• Heat oven to 350 degrees with the rack in the middle position.
• Line a 9 X 9 pan with a piece of parchment paper or aluminum foil, leaving enough hanging over the sides of pan to use as handles to easily lift the brownies out of the pan.
• Spray foil with cooking spray or grease with a little pat of butter. 

Mixing the Batter

• Add melted butter, brown sugar, and granulated to a large bowl and mix to combine.
• Next, add the sourdough discard, vanilla extract, and eggs, whisking until all of the ingredients are incorporated. 
• In a small bowl combine the flour, cocoa powder, and salt. Add the dry ingredients to the wet ingredients and mix until just combined.
• Fold the chocolate chips into the batter. Pour brownie batter into the prepared baking pan and smooth the top of the batter with an offset spatula. 

Bake

• Place the pan into the oven and bake for 40 minutes. The brownies are done if it's done insert a toothpick into the center of the brownies comes out clean. It's ok if there are a few moist crumbs, but if the toothpick comes out full of brownie batter, they aren't done and will need a few additional minutes.

Cool

• Remove the pan from the oven and place on a wire rack to cool completely before cutting. The brownies are delicate while still hot and will set up as they cool.

Long Ferment Option

Day 1

• Combine the flour, sourdough starter, sugars, and half a cup of melted butter in a bowl the night before you plan to bake the brownies. Cover the bowl and leave at room temperature for at least 8 hours and up to 24 hours.

Day 2

• Add the rest of the ingredients to the bowl of fermented brownie batter, stirring to mix well. Continue with baking directions above.