1. Preheat oven to 425°F (220°C) and line a baking sheet with parchment paper.

2. In a large bowl whisk together flour, baking powder, baking soda, salt, and sugar.

3. Cut cold butter into the dry ingredients until pea-sized crumbs form.

4. Stir in sourdough discard and cold milk until a soft dough forms, handling gently to avoid overmixing.

5. Turn dough onto a lightly floured surface, fold gently 2–3 times, then pat to 1-inch thickness.

6. Use a biscuit cutter to cut out 8 rounds and place them on the prepared baking sheet.

7. Brush biscuit tops with a little milk and bake for 12–15 minutes until golden brown; cool on a wire rack.

8. While biscuits bake, whisk eggs with milk, salt, and pepper and cook scrambled or bake in a muffin tin at 350°F (180°C) for 12–14 minutes to make egg rounds.

9. Slice cooled biscuits in half, layer cheese on the bottom halves, add eggs, ham, and optional fillings, then top with biscuit tops.

10. Wrap each sandwich in parchment or foil, label, and refrigerate for up to 4 days or freeze for up to 2 months.