Combine flour, sugar, nutmeg and baking powder in a large mixing bowl. Add milk and egg yolk and mix thoroughly.
Whisk egg whites until fluffy and gently fold into the flour mixture, forming a smooth batter.
Heat a frying pan over medium heat and spray lightly with oil. Pour the batter into a jug and pour enough batter into the pan to coat the bottom. Cook until small bubbles form on the surface, then flip over and cook for a further couple of minutes or until golden.