Melt butter in microwave first, so that it will cool a little before mixing into batter.
Preheat griddle to medium-high. If the griddle is not non-stick, lightly oil it first.
Optional: If desired, separate the egg and whip the egg white. This will help make the pancakes extra light and fluffy in texture. I use a little hand-held blender for this step. I always do this because it makes such a big difference.
In a good-sized mixing bowl, whisk together the dry ingredients. In a small separate bowl, whisk egg yolk, vanilla and melted butter. Combine the two mixtures in the larger bowl and mix.
Add club soda and egg whites and gently fold into batter. Be careful not to over-mix at this point.
If you did not separate the egg, you might need to use more club soda to reach the desired consistency. If you did separate the egg, the batter will be thicker than normal pancake batter.
I like to fry the pancakes in bacon grease, but you can use regular vegetable oil if you prefer. Pour about 1/3 c for each pancake and brown on both sides.
Brush the remaining melted butter on each pancake as you stack them.
I keep the pancakes on an oven-proof platter in the oven on 200 degrees while I get all of them cooked.
You will probably need to reapply the oil or bacon grease to the griddle.
If batter thickens while you finish the bacon or frying the first few batches, add the reserved club soda.
Unused batter can be kept covered in the fridge to use in the next few days. If it becomes too thick, add a little milk.