Preheat oven 200C/180C Fan/Gas 6.
For the soufflé mixture, place the melted butter in a pan with the red onion and cook for two minutes.
Remove from the heat and add the chopped herbs and allow to cool for three minutes.
For the white sauce, melt the butter and add the cornflour, plain flour, milk, cheese, salt and pepper and the egg yolks.
Take off the heat and allow to cool for two minutes.
For the egg whites, whisk the egg whites in a large bowl until they form stiff peaks.
Fold the white sauce into the egg whites and add the onion mixture. Do not over mix.
Grease two ramekin dishes and spoon the mixture into these.
Place on a tray in the pre-heated oven for eight minutes.
Serve the soufflés in the dishes straight away.