Brush 4 small ramekins with melted butter to grease.
Heat the butter in a saucepan, add the flour and cook, stirring, for 1 minute. Gradually add the milk and cook, stirring all the time, until thickened and smooth. Remove from the heat and cool a little. Stir in the blue cheese, half the Parmesan, the mustard, herbs and egg yolks and season well.
Whisk the egg whites in a clean bowl until they form soft peaks, then gently fold into the cheese sauce. Spoon into the prepared ramekins, then place in a roasting tin. Pour boiling water into the tin to come halfway up the ramekins and then place in a preheated oven, 180°C (350°F), Gas Mark 4, for 15–20 minutes until firm. Cool completely.
Mix together the cream and the remaining Parmesan when ready to serve and spoon over the soufflés. Place in a preheated oven, 220°C (425°F), Gas Mark 7, for 10–15 minutes or until golden and risen. Serve with a watercress salad.