1. Preheat the oven to 350 degrees F and line a 9x9 inch metal baking pan with parchment paper for easy removal. Set to the side.
2. Add the butter and chocolate chips to a large microwave-safe bowl. Melt butter and chocolate in 30-second increments, mixing until smooth.
   113 grams unsalted butter, 270 grams chocolate chips
3. Sift the cocoa powder, salt, and espresso powder together and add to the melted chocolate. Stir until smooth.
   50 grams unsweetened cocoa powder, 6 grams salt, 2 grams espresso powder, optional
4. Next, add the white sugar and brown sugar and stir until combined.
   175 grams white sugar, 175 grams light brown sugar
5. Whisk in the eggs one at a time and mix until smooth, then stir in the sourdough discard and vanilla extract until the white streaks are gone.
   2 large eggs, 4 grams vanilla extract, 120 grams sourdough discard, room temperature
6. Lastly, fold in the flour until just incorporated.
   140 grams all-purpose flour, sifted
7. Pour the batter into the prepared pan and smooth the chocolate mixture with a rubber spatula.
8. Bake for 35-40 minutes.

   These brownies are super fudgy and gooey, so the toothpick test isn't the most reliable way to check if the brownies are finished baking. Instead, I look to see if the sides of the brownies are pulling away from the edges of the parchment paper and the center looks a little soft. Careful not to overbake. The brownies will continue to cook even out of the oven, so it's better to undercook than overcook them.
9. Remove the warm brownies from the oven, place them on a wire rack, and cool them completely before topping them with the chocolate ganache.

Chocolate Ganache

1. Place the chocolate chips in a small bowl. Set aside.
   180 grams chocolate chips
2. Add heavy cream to a small saucepan. Heat on medium until warm, do not bring to a boil, then pour the warm cream over the chocolate chips. Let it sit for 1-2 minutes, then stir until silky smooth.
   90 grams heavy cream
3. Pour the chocolate ganache on top of the brownies. Spread to the edges with an offset spatula and sprinkle the rainbow sprinkles on top. I love these ones!
   Rainbow Candy-Coated Chocolate Chips
4. Allow the sourdough cosmic brownies to set before slicing. Just know that this can take a bit at room temperature. A quicker option is to cover and place the brownies in the fridge for 30 minutes. Enjoy!
5. How to Slice - Slice the pan of brownies in half, then slice each half into 4 long pieces. To get the iconic look, score the middle of each brownie. Or just cut into 16 smaller brownies. Use a hot wet paper towel and wipe off your knife for clean cuts.