Preheat your oven to 350°F (175°C). Grease an 8x8-inch baking pan or line it with parchment paper.
Start by browning the butter. In a small pan or skillet, add the butter and turn the heat to medium. The butter will melt and start to bubble. Once it meltes and begins to foam, stir with a spatula or whisk to keep it moving. After a few minutes, you’ll see golden-brown bits form at the bottom of the pan, and you’ll start to smell a nutty smell. Remove from the heat immediately!
Once the butter is browned, add remove it from the heat. Than add in 1 cup of chocolate chips. Mix until they're melted. Set aside and let cool.
In a medium bowl, add in the eggs and both sugars. Using a hand mixer, mix on medium high for 3-5 minutes. You want it to get light and fluffy. This really helps the texture of the brownies.
Then, add in the sourdough discard and vanilla extract. Mix again until incorporated. Add in the butter and chocolate mixture and mix well.
Sift in the cocoa powder, flour, and sea salt. Then gently fold everything in together using a rubber spatula. Be careful not to overmix.
Pour in ⅓ cup chocolate chips if you're using them and fold in one more time.
Pour the mixture into the greased pan and bake for 40-45 minutes. Top with flaky sea salt, cut, and enjoy!