1. In a large mixing bowl, whisk together the all-purpose flour, baking powder, baking soda, salt, and black pepper. Make sure everything is well combined to ensure even leavening.

2. Add the cold, cubed butter to the dry ingredients. Using a pastry blender, two knives, or your fingertips, cut the butter into the flour mixture until it resembles coarse crumbs with some pea-sized pieces of butter remaining. This is crucial for a flaky scone.

3. Gently fold in the shredded cheddar cheese until it’s evenly distributed throughout the flour mixture. Avoid overmixing at this stage.

4. In a separate small bowl, whisk together the sourdough discard and cold milk. Pour the wet mixture into the dry ingredients. Use a fork or your hands to mix until just combined. The dough will be shaggy and slightly sticky, but avoid overworking it. Overmixing develops gluten, which can lead to tough scones.

5. Turn the dough out onto a lightly floured surface. Gently pat it into a round disc about 1-inch thick. Use a sharp knife or a round cookie cutter (about 2.5-3 inches) to cut out 8-10 wedges or rounds. If using a knife, cut the disc into 8 triangles.

6. Preheat your oven to 400 F (200 C). Line a baking sheet with parchment paper. Carefully transfer the shaped scones to the prepared baking sheet, leaving a little space between them. If using, brush the tops of the scones with the beaten egg wash for a golden finish.

7. Bake for 20-25 minutes, or until the scones are golden brown on top and cooked through. A toothpick inserted into the center should come out clean.

8. Remove the scones from the oven and let them cool on the baking sheet for a few minutes before transferring them to a wire rack to cool slightly. Serve warm, sprinkled with fresh chives or parsley if desired.