butter, for greasing
100g caster sugar, plus 1 tbsp for dusting
3 egg yolks
40g plain flour
4 tbsp Grand Marnier
finely grated zest 2 oranges
5 egg whites
icing sugar, for dusting
Thoroughly grease a 15 x 9cm deep soufflé dish with butter, then coat the inside with 1 tbsp sugar. Whisk half the remaining sugar with the egg yolks until thick, pale and mousse-like. Sift the flour over the surface, then fold in very gently with a metal spoon.
Heat the milk until boiling, then whisk into the egg yolks. Return the mixture to the pan and cook over a medium heat, stirring continuously,
until just thickened and smooth. Remove from the heat and stir in the Grand Marnier and orange zest. Cover the surface and leave to cool.
Heat oven to 220C/200C fan/gas 7. Whisk the egg whites until they form stiff, moist-looking peaks. Gradually whisk in the remaining sugar, a teaspoon at a time, until thick and glossy. Using a metal spoon, fold a little of the whisked egg white into the cooled Grand Marnier mixture
to loosen, then gently fold in the remaining egg whites.
Carefully spoon the mixture into the soufflé dish, then bake in the oven for 17-20 mins or until the soufflé is well risen, the top is browned and there is a slight wobble to the centre. Dust with icing sugar and serve immediately.