250 g (8 oz) frozen chopped spinach, thawed, or 500 g (7 lb) fresh spinach
knob of butter
4 eggs, separated
25 g (7 oz) Parmesan cheese, grated
salt and freshly ground black pepper
oak leaf lettuce, to garnish
15 g (1/2 oz) butter
175 g (6 oz) closed cup mushrooms, sliced
1 tablespoon plain flour
150 ml (1/4 pint) milk
pinch of nutmeg
1. Line a 30 x 20 cm (72 x 8 inch) Swiss roll tin with greaseproof paper and then oil lightly, or make a case of the same measurements with aluminium foil.
2. Place the spinach in a saucepan with a knob of butter and cook until completely softened. Drain the spinach well, chop if fresh and place in a large bowl. Add the egg yolks, beating them well into the chopped spinach and season to taste.
3. Whisk the egg whites in a large grease-free bowl until just holding their shape. Using a metal spoon, quickly fold them into the spinach mixture. Turn the mixture into the prepared Swiss roll tin, sprinkle the grated Parmesan over the surface, and bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 10 minutes.
4. Meanwhile make the filling. Heat the butter in a small saucepan. Add the sliced mushrooms and gently fry until softened. Stir in the flour and cook, stirring continuously for a further 1 minute. Slowly stir in the milk and cook the sauce until thickened. Stir in the nutmeg and seasoning to taste.
5. Remove the spinach roulade from the oven and turn out on to a sheet of greaseproof paper. Quickly spread the mushroom filling over the surface and gently roll the roulade up. Cut into thick slices and serve immediately with a lettuce garnish.