In a large mixing bowl, use a balloon whisk to mix together the dry ingredients
In a jug, combine the buttermilk, cooled butter and egg yolks
Add to the dry ingredients and mix until just combined
In a separate, small bowl, whisk the egg whites to form soft peaks
Fold a small amount of the whisked egg whites into the batter to loosen, then fold through the rest of the egg whites.
Fold through the grated apple
Heat a medium sized non-stick frypan over medium-low heat
Brush pan with a little of the extra melted butter, then pour in about ⅓ cup of batter. A soup ladle or measuring cup works well for this. Tilt the pan a little, to help spread the batter
Cook for 1-2 minutes, until pancake is bubbling (it should be golden when you turn it)
Flip over pancake and cook for another minute. Remove and keep warm, while cooking the rest of the pancakes