1. Prepare Your Muffin Tin: Start by preheating your oven to 375 F (190 C). Line a 12-cup muffin tin with paper liners or grease it thoroughly. This prevents sticking and makes for easy cleanup.

2. Combine Dry Ingredients: In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, unsweetened cocoa powder, baking soda, and salt. Make sure there are no lumps and the ingredients are evenly distributed.

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.

4. Combine Wet and Dry: Pour the wet ingredients into the bowl with the dry ingredients. Stir gently with a spatula or wooden spoon until just combined. It’s crucial not to overmix; a few lumps are perfectly fine and will result in tender muffins. Overmixing can lead to tough muffins.

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

6. Fill Muffin Cups: Divide the batter evenly among the 12 prepared muffin cups, filling each about two-thirds full. For an extra touch, you can sprinkle a few more chocolate chips on top of each muffin before baking.

7. Bake the Muffins: Bake for 18-22 minutes, or until a wooden skewer or toothpick inserted into the center of a muffin comes out clean or with moist crumbs attached. The tops should be set and lightly spring back when gently touched.

8. Cool and Serve: Let the muffins cool in the muffin tin for 5 minutes before transferring them to a wire rack to cool completely. They are delicious warm, but also great at room temperature.