Preheat the oven to 200C/400F/Gas 6.
Place the Stilton, port and cream into a small non-stick ovenproof frying pan. Heat gently until the cheese has melted and the mixture is smooth.
Remove from the heat and stir in the egg yolk.
In a bowl, whisk the egg whites with the lemon juice until stiff peaks form when the whisk is removed. Fold the egg whites into the cheese mixture.
Transfer to the oven and bake for 6-8 minutes, or until well risen and lightly golden on top.