Melted butter, for greasing
Extra 50g butter, chopped
3/4 cup plain flour
1 1/3 cups milk
150g gruyere, grated
4 eggs, separated
1 Tbsp finely chopped chives
1/4 tsp sea-salt flakes
6 Tbsp thickened cream
Extra 20g gruyere, grated
Extra chives, to serve
Baby green salad leaves, to serve
Note: Allow overnight chilling
Grease six 1-cup capacity ramekins with melted butter, then line base with baking paper. Arrange ramekins in a large deep roasting tin, leaving a 2cm gap between each one. Set aside.
Melt extra butter in a small saucepan over a medium heat. Add flour and stir until combined (this is a dry mix). Add milk, 1/4 cup at a time, whisking continuously until each addition has been completely incorporated. Cook mixture for a further 30 seconds or until smooth and combined
Add gruyere and stir with a wooden spoon until smooth.
Remove pan from heat and add egg yolks and chives, stirring until smooth and combined. Set aside for 15 minutes to cool.
Meanwhile, preheat oven to 180°C. Put eggwhites and salt in the bowl of an electric mixer and beat for 5 minutes or until soft peaks form. In 2 batches, gently fold eggwhite mixture into cooled cheese mixture until smooth and combined.
Divide mixture between prepared ramekins. Pour enough water into roasting tin to reach halfway up sides of ramekins. Bake for 20 minutes or until golden. Remove tin from oven and set aside to cool.
Line an oven tray with baking paper. When cool enough to handle, carefully turn soufflés out onto prepared tray. Loosely cover with plastic wrap and refrigerate for at least 2 hours, or preferably overnight.
Preheat oven to 180°C. Spoon 1 Tbsp of the cream over each soufflé and scatter over extra gruyere. Bake for 20-25 minutes or until puffed and golden. Divide soufflés among serving plates and sprinkle over extra chives. Serve immediately with baby green salad leaves on the side.