01 - Combine active sourdough starter, all-purpose flour, granulated sugar, and whole milk in a large mixing bowl. Stir until the mixture is smooth. Cover loosely with plastic wrap or a lid and allow to rest at room temperature for 8 to 12 hours.
02 - In a small bowl, whisk eggs until well blended. Add eggs, melted butter, fine sea salt, baking soda, and vanilla extract to the overnight batter. Gently mix until incorporated, being careful not to overmix. Batter should be slightly bubbly and expanded.
03 - Heat a nonstick skillet or griddle over medium heat. Brush the surface lightly with melted butter for an even coating.
04 - Pour 1/4 cup of batter for each pancake onto the heated skillet. Cook until bubbles appear and edges are set, approximately 2 to 3 minutes. Flip and continue cooking for 1 to 2 minutes until golden brown and cooked through. Repeat with remaining batter, adding butter as needed.
05 - Serve pancakes hot with maple syrup, fresh fruit, or preferred toppings.