Preheat oven to 375°F (190°C).

Butter 4 ramekins and coat with sugar.

Whisk flour, sugar, and milk in a saucepan over medium heat until thickened.

Remove from heat and whisk in egg yolks and vanilla.

Beat egg whites and cream of tartar until soft peaks form.

Gradually add sugar and beat until stiff peaks form.

Gently fold 1/3 of whites into the base, then fold in the rest.

Pour into ramekins and bake for 12-15 minutes until risen.