Melt 50g butter in a saucepan, then add 50g flour and mix again.
Slowly add 250ml hot milk while whisking continuously until it thickens like a béchamel sauce.
Take off the heat and add 1tbsp butter, a sprinkle of grated nutmeg, salt and pepper, and mix well again.
Add 4 egg yolks, one after the other, whisking between each addition.
Mix in 150g grated emmental, gruyere or cheddar.
Beat the 4 egg whites until stiff and carefully fold them into the mixture.
Butter a soufflé dish well and add grated cheese all around before pouring the mix in.
Bake in a fan oven at 180°C for 30-35 minutes, or until risen, golden on top and cooked through.