Mix wet ingredients — In a large bowl, whisk together chocolate sourdough starter, eggs, yolk, milk, vanilla, and maple syrup (reserve the butter and chocolate chips for later).
Add dry ingredients — Stir in flour, cocoa, sugar, salt, baking powder, and baking soda until just combined.
Whisk in butter — Gently whisk in the melted or browned butter.
Optional overnight ferment — For deeper flavor, ferment the batter overnight in the fridge. If doing so, add the baking powder and baking soda the next day right before cooking.
Cook — Heat a lightly buttered or oiled skillet over medium heat. Pour about ⅓ cup batter per pancake. Sprinkle on chocolate chips if desired before flipping.
Flip once bubbly — When bubbles form on the surface, flip and cook until set.
Serve — Enjoy warm with syrup, whipped cream, or a dusting of powdered sugar.
