When I tested these I discovered that the longer the batter rests, the better the pancakes. If you can, make the batter the night before and let it rest in the refrigerator overnight. In the morning, remove it from the fridge, give it a stir, and let it come to room temperature before making the pancakes.
Sift the all purpose flour, sugar, baking powder, baking soda, and salt together into a bowl.
Combine the buttermilk, unsalted butter, eggs, and vanilla in a separate bowl.
Slowly add the wet ingredients to the dry, whisking, just until combined.
Cover with plastic and let rest for at least 30 minutes.
Heat a nonstick pan on medium heat.
Add some of the butter and then 1/3 cup batter.
Turn heat down to medium-low.
Cook until the top of the pancake bubbles and flip, cooking until the other side is lightly golden brown, about 2 to 3 minutes per side.
Repeat with the remaining butter and batter.
Serve with maple syrup.