In a saucepan over medium-low heat, melt the two sticks of butter. Let the butter come to a low boil and whisk continually for 2-3 minutes or until the butter turns amber and begins to smell nutty.
2 sticks of butter
Remove the browned butter from the heat and add in the cup of cocoa powder and 3/4 cup of semisweet chocolate. Stir until the chocolate is completely melted.
1 Cup cocoa, 1/2 Cup semi sweet chocolate chips
Add the powdered sugar, table sugar, and brown sugar into the warm chocolate mixture and stir until the sugars mostly dissolve.
1 1/2 Cup powdered sugar, 1/4 Cup Table Sugar, 1 Cup light brown sugar
In a small bowl, whisk the three large eggs and egg yolk together until they are thoroughly combined, light and fluffy. Once the chocolate has cooled slightly, whisk the eggs into the chocolate. Stir vigorously to continue dissolving any remaining sugar granules.
3 eggs + 1 egg yolk
Next, add in the Tbsp of vanilla and the 1/2 Cup of sourdough starter discard.
1 Tbsp Vanilla Extract, 1/2 Cup discard
Mix the flour and the salt into the batter. Stir until it is all incorporated.
3/4 Cup Flour, 3/4 tsp Kosher salt
At this point, allow the brownie batter to ferment on the counter for up to two hours OR in the fridge overnight.
Preheat the oven to 350 degrees. Grease a 9 X 13 baking dish with oil and pour the prepared batter into the baking dish. Place the brownies into the preheated oven on the middle rack for 35 minutes or until the tops are crinkled and appear set.
Allow the brownies to cool for AT LEAST 30 minutes before cutting them into 12 pieces- preferably wait until they're completely cooled. Serve with vanilla ice cream for an extra special treat!