Preheat the oven to 180°C (350°F).
In a saucepan, heat the milk until warm.
In a mixing bowl, whisk the egg yolks and sugar until pale and thick.
Add the flour to the egg yolk mixture and mix well.
Gradually add the warm milk, whisking constantly.
Return the mixture to the saucepan and cook over low heat until thickened.
Remove from heat and stir in the vanilla extract. Let it cool.
In a separate bowl, whisk the egg whites with a pinch of salt until stiff peaks form.
Gently fold the egg whites into the cooled mixture.
Pour the mixture into greased ramekins and bake for 20-25 minutes until risen and golden.