1. Cream the Butter and Sugars: In a large mixing bowl, using an electric mixer, cream together the softened unsalted butter, granulated sugar, and light brown sugar until the mixture is light and fluffy. This usually takes about 2-3 minutes. Scrape down the sides of the bowl as needed to ensure everything is well combined.

2. Add Wet Ingredients: Beat in the large egg and vanilla extract until fully incorporated. Then, add the room temperature sourdough discard and mix on low speed until just combined. The mixture might look a little curdled at this stage, but don’t worry, it will come together.

3. Combine Dry Ingredients: In a separate medium bowl, whisk together the all-purpose flour, baking soda, and salt. Make sure these dry ingredients are thoroughly mixed to ensure even distribution in the dough.

4. Gradually Add Dry to Wet: Slowly add the dry ingredient mixture to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix the dough, as this can lead to tougher cookies. Stop mixing as soon as no streaks of flour are visible.

5. Fold in Chocolate Chips: Gently fold in the semi-sweet chocolate chips by hand using a spatula. Distribute them evenly throughout the dough.

6. Prepare for Baking: Preheat your oven to 375 F (190 C). Line a baking sheet with parchment paper. Drop rounded tablespoons of cookie dough onto the prepared baking sheet, leaving about 2 inches between each cookie to allow for spreading.

7. Bake Until Golden: Bake for 10-12 minutes, or until the edges are lightly golden brown and the centers are still slightly soft. The cookies will continue to set as they cool.

8. Cool and Enjoy: Remove the baking sheet from the oven and let the cookies cool on the sheet for 5 minutes before transferring them to a wire rack to cool completely. This helps them firm up without breaking.