Method

1. Preheat the oven to 220°C. Place the bacon around the inside edges of 2 x 250ml ramekins. Place the ramekins on a baking tray and bake for 5minutes, then reduce the oven temperature to 200°C.
2. Meanwhile, melt the butter in a small saucepan over a low heat. Stir in the flour for 1 minute. Gradually add the milk, stirring, until smooth. Cook, stirring, for 1 minute or until thickened. Remove from the heat. Stir in the Gruyere, Cheddar and Parmesan and the egg yolk. Season.
3. Using an electric mixer, beat the egg whites in a large, clean, dry bowl until soft peaks form. Stir large spoonfuls of the egg white into the cheese mixture. Spoon into the prepared ramekins. Bake for 12 minutes or until well risen. Serve immediately.