Peel the apples and cut into slices about 5 mm thick. Drizzle with lemon juice and let rest for 10 minutes.
For the batter, mix milk, egg yolks, flour, butter, vanilla sugar and oil well. Beat the egg whites with a pinch of salt until stiff and gently fold into the mixture.
Mix sugar with cinnamon. Heat the frying oil, dip the apple slices into the batter and fry on both sides until golden. Drain on kitchen paper and sprinkle with the cinnamon-sugar mixture while still warm.