Preheat the oven to 200°C and place a roasting tin with 4 cm of hot water in there.
Butter a 1 litre soufflé dish.
Boil the chard for 6 minutes or until tender.
Squeeze all the water out (I used my potato ricer).
Blend the chard to form a puree (I used a stick blender).
Put the milk, butter and flour in a pan over a medium heat and whisk until you have a smooth glossy paste.
Add the cheddar and beat until it melts.
Put the chard puree and cheese paste in a bowl and mix in the cayenne, nutmeg, salt and pepper.
Taste and adjust the seasoning if necessary.
Next separate the eggs and add 2 of the yolks to the chard mixture and mix in.
In a large, clean, greaseless bow beat the egg whites until they form stiff peaks (don't over whisk).
Add 1 tbsp to the puree, then fold in the rest, cutting in with a large metal spoon.
Spoon into the prepared soufflé dish and top with the grated Parmesan or Cheddar.
Place in the oven for 30 – 35 minutes until well risen and the top is starting to crack (don't over cook the centre should be moist).