1. Preheat your oven to 375 F (190 C). Line two large baking sheets with parchment paper or silicone baking mats.

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

3. Beat in the egg and vanilla extract until fully incorporated. Then, add the sourdough discard and mix until just combined. The mixture might look a little curdled at this point, but don’t worry, it will come together.

4. In a separate medium bowl, whisk together the all-purpose flour, baking soda, and salt. This ensures the leavening and seasoning are evenly distributed throughout the dough.

5. Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix; stop as soon as no streaks of flour remain. Overmixing can lead to tough cookies.

6. Gently fold in the chocolate chips, mini marshmallows, and graham cracker crumbs by hand using a spatula. Distribute them evenly throughout the dough.

7. Drop rounded tablespoons of dough onto the prepared baking sheets, leaving about 2 inches between each cookie. If desired, lightly press a few extra mini marshmallows and small graham cracker pieces onto the top of each cookie before baking for an extra s’mores look. Bake for 10-12 minutes, or until the edges are lightly golden and the centers are still slightly soft. The marshmallows will be puffed and lightly toasted.

8. Remove the cookies from the oven and let them cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely. This allows them to set up properly and prevents them from breaking.