Classic Cheese Soufflé

• 2 oz (50 g) butter
• 1½ oz (40

Pre-heat the oven to gas mark 5, 375°F (190°C).

Melt the butter in a large pan. Stir in the flour and cook for 1 minute. Remove from the heat and gradually blend in the milk. Heat, stirring, until thickened. Beat in the egg yolks and the cheeses. Season with the mustard, and sa