1. 1. Prepare your skillet: Preheat your oven to 375 F (190 C). Lightly grease a 9-inch cast iron skillet or an oven-safe baking dish with butter. This prevents sticking and helps create a lovely golden crust.

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

3. 3. Mix wet ingredients: In a separate medium bowl, combine the sourdough discard, milk, and melted butter. Whisk until everything is well combined and smooth. The discard should be fully incorporated into the liquid mixture.

4. 4. Combine wet and dry: 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; a few small lumps are perfectly fine and will result in a tender bread. Overmixing can lead to a tough texture.

5. 5. Fold in the cheese: Add the shredded cheddar cheese to the batter. If you’re using chives or green onions, fold them in now as well. Gently mix until the cheese is evenly distributed throughout the dough.

6. 6. Transfer to skillet and bake: Spoon the batter into your prepared skillet, spreading it evenly with the back of your spoon or a spatula. Place the skillet in the preheated oven and bake for 20-25 minutes, or until the top is golden brown and a wooden skewer or toothpick inserted into the center comes out clean.

7. 7. Cool and serve: Once baked, remove the skillet from the oven. Let the bread cool in the skillet for 5-10 minutes before slicing and serving. This allows it to set slightly and makes for easier slicing.