preheat oven to 200C/Gas6
drain the spinach thoroughly and mix with the nutmeg, pepper and chopped walnuts and place in a greased ovenproof dish
top with the salmon
melt the butter in a saucepan, add flour and cook, stirring for 2 minutes
slowly add milk and bring to the boil stirring, until thickened
whisk in egg yolks and cheese
stir in the chopped chives
in a clean bowl, whisk egg whites until stiff and fold into cheese sauce
spread sauce over salmon and bake for 30 minutes until golden brown
serve immediately
6 servings