1. Prepare Your Oven and Muffin Tin: Start by preheating your oven to 400 F (200 C). Line a 12-cup muffin tin with paper liners or grease it well with butter or non-stick spray. This ensures your muffins won’t stick and makes for easy cleanup.

2. Combine Dry Ingredients: In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, baking soda, and salt. Make sure there are no lumps and everything is evenly distributed. This step is crucial for even rising.

3. Mix Wet Ingredients: In a separate medium bowl, whisk together the sourdough discard, milk, melted butter, egg, and vanilla extract until well combined and smooth. The melted butter should be cooled slightly so it doesn’t scramble the egg.

4. Combine Wet and Dry Mixtures: Pour the wet ingredient mixture into the bowl with the dry ingredients. Stir gently with a spatula or wooden spoon until just combined. Be careful not to overmix the batter; a few lumps are perfectly fine and will lead to a more tender muffin. Overmixing can result in tough muffins.

5. Fold in Chocolate Chips: Gently fold in the chocolate chips until they are evenly distributed throughout the batter. Again, avoid overmixing.

6. Fill Muffin Tin: Divide the batter evenly among the 12 prepared muffin cups. Each cup should be about two-thirds full. You can use an ice cream scoop for easy and consistent portioning.

7. Bake Until Golden: Place the muffin tin in the preheated oven and bake for 20-25 minutes, or until the tops are golden brown and a wooden skewer or toothpick inserted into the center of a muffin comes out clean.

8. Cool and Serve: Once baked, remove the muffin tin from the oven and let the muffins cool in the tin for 5 minutes before transferring them to a wire rack to cool completely. Enjoy them warm or at room temperature!