1. 1. Prepare your baking pan and oven: Preheat your oven to 350 F (175 C). Lightly grease an 8×8 inch square baking pan with butter or cooking spray, then line it with parchment paper, leaving an overhang on two sides to easily lift the brownies out later. This step prevents sticking and makes for clean slicing.

2. 2. Melt the butter and combine with sugar: In a medium-sized mixing bowl, melt the unsalted butter either in the microwave or on the stovetop. Once melted, add the granulated sugar and whisk them together until well combined and the mixture is smooth.

3. 3. Add wet ingredients: To the butter and sugar mixture, crack in the two large eggs, one at a time, whisking well after each addition until fully incorporated. Stir in the vanilla extract and then the sourdough discard, mixing until the batter is smooth and uniform.

4. 4. Combine dry ingredients: In a separate small bowl, whisk together the all-purpose flour, unsweetened cocoa powder, baking soda, and salt. Ensure there are no lumps of cocoa powder.

5. 5. Mix wet and dry ingredients: Gradually add the dry ingredient mixture to the wet ingredients, mixing with a spatula or wooden spoon until just combined. Be careful not to overmix the batter; stop as soon as no streaks of flour are visible. If using, gently fold in the chocolate chips at this stage.

6. 6. Bake the brownies: Pour the brownie batter into your prepared 8×8 inch baking pan and spread it evenly with a spatula. Place the pan in the preheated oven and bake for 25-30 minutes. The brownies are done when a toothpick inserted into the center comes out with moist crumbs, but not wet batter. Overbaking will result in dry brownies.

7. 7. Cool and serve: Once baked, remove the pan from the oven and let the brownies cool completely in the pan on a wire rack before lifting them out using the parchment paper overhang. This cooling time is crucial for achieving that perfect fudgy texture and clean slices. Once cooled, slice into squares and enjoy!