Separate egg white and yolk into two separate bowls. White in a small bowl, yolk into a medium bowl
Add buttermilk and baking soda to egg yolk, and whisk well.
Sift flour, sugar, salt, and baking powder into buttermilk mixture and lightly mix until flour is just moistened. Lumps are ok! Do not over mix!
Fold in soft butter, until it's mostly incorporated, there should still be lumps!
With a hand mixer or a whisk, beat egg whites to firm peaks. Add to batter mixture and fold in until white streaks are mostly incorporated. Set aside for 5 minutes.
Preheat griddle to medium
With a large scoop or spoon, add rounds of batter to hot pan. (see note below about preparing pan)
When bubbles form on top of batter, and bottom is golden brown, about 2 minutes, flip. Cook for additional 2 minutes or until cakes are cooked through. Repeat until batter is done.