The morning before, whisk together the milk, yogurt, starter, flour and sugar in a bowl. Cover and place in the refrigerator for 24 hours.
Remove the mixture from the fridge and let sit at room temp for 30 minutes.
Whisk the baking soda, baking powder, salt, butter and yolks into the flour mixture.
In a separate bowl, whisk the egg whites until stiff peaks form. Fold the whites into the batter.
Heat a large skillet over medium-low heat for 2 minutes. Add 1 tablespoon butter and swirl the pan to coat. Spoon pancake batter, about 1/4 cup each, into pan and cook until edges are set and the first side is golden, about 2-4 minutes. Flip the pancakes and continue cooking until the second side is golden brown, about 2-3 minutes. Repeat with remaining batter.
Serve with butter, maple syrup, or any other toppings of your choice.