1. Preheat your oven to 350 F (175 C). Lightly grease and flour an 8×8 inch baking pan, or line it with parchment paper, leaving an overhang on two sides to easily lift the bars out later.

2. In a large mixing bowl, melt the butter. Once melted, stir in the granulated sugar and vanilla extract until well combined. Then, add the unfed sourdough discard and mix until everything is smooth and thoroughly incorporated.

3. In a separate medium bowl, whisk together the all-purpose flour, baking soda, and salt. Ensure there are no lumps and the leavening agent is evenly distributed.

4. 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.

5. Gently fold in the chocolate chips until they are evenly distributed throughout the batter.

6. Pour the 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, or until the edges are golden brown and a toothpick inserted into the center comes out with moist crumbs, but not wet batter.

7. Once baked, remove the pan from the oven and let the bars cool completely in the pan on a wire rack.

8. Once fully cooled, use the parchment paper overhang to lift the entire slab of bars out of the pan. Place it on a cutting board and slice into 16 squares. Serve and enjoy!