Make roux with butter and flour and then add seasoned hot milk to form bechamel.
Add cheese and truffle oil to bechamel and mix in well.
Slowly add 1 yolk at a time to the cool cheese bechamel until all egg yolks are included.
Beat egg whites until stiff peaks and slowly fold into cheese batter to form a light souffle mix.
Pour mix into ramekins that have been lined with butter and flour.
Bake in Bain Marie at 180º until cooked.