1. 1. Combine Dry Ingredients in the Evening: In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, baking soda, and salt. Make sure there are no lumps.

2. 2. Add Wet Ingredients (Evening): To the dry ingredients, add the sourdough discard, eggs, milk, melted and cooled butter, and vanilla extract. Stir everything together until just combined. The batter will be thick and shaggy; do not overmix.

3. 3. Cover and Chill Overnight: Cover the bowl tightly with plastic wrap or a lid and place it in the refrigerator. Let the batter rest overnight for at least 8 hours, or up to 12 hours. This resting period is crucial for developing the sourdough flavor and texture.

4. 4. Preheat Waffle Iron in the Morning: The next morning, take the batter out of the fridge and let it sit at room temperature while your waffle iron preheats. Preheat your waffle iron according to the manufacturer’s instructions. Lightly spray or brush the grids with non-stick cooking spray or melted butter.

5. 5. Cook the Waffles: Pour or scoop the batter onto the hot waffle iron, filling it about two-thirds full. Close the lid and cook for 3-5 minutes, or until the waffle is golden brown and crispy, and steam stops coming out of the sides. Cooking time will vary based on your waffle iron.

6. 6. Serve Immediately: Carefully remove the cooked waffle from the iron and transfer it to a plate. Repeat with the remaining batter. For best results, serve the waffles immediately while they are warm and crisp.