In a bowl, whisk flour, baking powder, and salt. Keep aside.
In a different bowl, beat egg yolk with vanilla, add butter, milk, yogurt, and sugar. Beat until well combined.
Add the flour to the egg and butter mixture, and mix gently. You will see lumps, ignore the lumps and don't over mix.
In another bowl beat the egg white until you get stiff peak.
Add the egg white and blueberries to the previously prepared batter. Gently fold.
Some egg whites should be seen in the batter, that means you didn't over mix it.
Heat a frying pan to medium low. I didn't use any oil or butter since I'm using a non-stick pan.
Pour 1/4 cup from the batter onto the hot pan.
Cook for about two minutes or until the pancake's bottom is golden. flip the pancake gently.
Cook the other side until golden then remove from heat.
Note 1: Do not press the pancake down while it's cooking.
Note 2: These pancakes when cold will wrinkle a bit, especially if kept in fridge. Do not worry, the moment you re-heat them they will look and taste fresh even the second day.