Prepare the soufflé tin according to the method of cooking. If the soufflé is to be baked, butter the mould well, if steamed.
Melt the butter, stir in the flour and cook gently for a few minutes without colouring. Add the milk, stir well until smooth. Reheat, stirring continuously until the mixture thickens and leaves the sides of the pan. Leave to cool. Beat in the egg yolks, sugar and vanilla essence. Whisk the egg whites stiffly and fold them in lightly. Pour the mixture into the mould or tin and cover.
Steam for ¾–1 hr. or bake in a fairly hot oven (375° F., Gas 5) for 30–35 min.