1. Preheat your oven to 375 F (190 C). Line a 12-cup standard muffin tin with paper liners or grease it thoroughly with non-stick spray.

2. In a large mixing bowl, whisk together the all-purpose flour, baking powder, baking soda, salt, and black pepper. Make sure there are no lumps and the ingredients are evenly distributed.

3. In a separate medium bowl, whisk together the sourdough discard, milk, olive oil (or melted butter), and egg until well combined and smooth. The sourdough discard should be at room temperature for easier mixing.

4. Pour the wet ingredient mixture into the dry ingredient mixture. Stir gently with a spatula or wooden spoon until just combined. Be careful not to overmix; a few lumps are perfectly fine and will result in a tender muffin. Overmixing develops gluten, leading to tough muffins.

5. Gently fold in the shredded cheddar cheese, chopped cooked ham (or bacon bits), and fresh chives (or green onions) into the batter. Distribute them evenly throughout the mixture.

6. Divide the batter evenly among the 12 prepared muffin cups. You can use a large spoon or an ice cream scoop for easy portioning. Fill each cup about two-thirds full.

7. 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. 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. Serve warm or at room temperature.