In a large bowl, whisk together the flour, sugar, and baking powder.
In another bowl, combine milk, egg yolk, and vanilla extract. Gradually add this mixture to the dry ingredients, stirring until smooth.
Fold the whipped egg whites into the batter gently to preserve the airiness.
Heat a non-stick pan over low heat and pour in pancake batter to form small, thick rounds. Cover the pan and cook until bubbles appear and the edges are set, about 5 minutes.
Carefully flip and cook the other side until golden, another 3-5 minutes. Serve immediately with syrup or toppings of choice.
Notes
For best results, serve these pancakes freshly made and hot. Avoid overcrowding the pan to ensure even cooking.