Preheat the oven to 200C/400F/Gas 6.
Mix the egg yolks with the blue cheese in a bowl.
Add the whisked egg whites and cornflour and gently fold into the mixture.
Heat the butter and the oil in a 20cm/6in ovenproof frying pan, until the butter is foaming. Pour the cheese and egg mixture into the pan and transfer to the oven to bake for 8-10 minutes, or until puffed up and cooked through.
Sprinkle with black pepper and serve immediately.
