Line the base and ends of a swiss roll tin 25 x 30cm with greaseproof paper, using enough paper to over hung by 5cm at both ends. Spray with non-stick spray and dust with flour. Preheat oven to 200C (400F). Trim thick stems from spinach and wash leaves. Pack into a heavy saucepan, add a pinch of salt, cover tightly and cook on low heat, shaking saucepan frequently, 4-5 minutes, or until spinach is wilted and tender. Drain and, when cool enough to handle, squeeze spinach to remove as much moisture as possible and chop fine. Put spinach into a bowl and stir in cream, nutmeg, pepper, 1 teaspoon salt and lightly beaten egg yolks. Beat the egg whites until they hold soft peaks and fold into spinach mixture. Spread the mixture in the lined tin and sprinkle with parmesan. Bake just above the centre of the oven for 10-12 minutes or until firm. While roulade is baking, make filling by combining all ingredients. Remove roulade from oven and invert on to another piece of oiled greaseproof paper. Peel off the first piece of paper and spread roulade with filling. Roll up, using the paper to help, and rolling roulade on to a heatproof serving platter with the last turn. Return to oven for a few minutes to reheat. Serve with mushroom sauce. Serves 6. SAUCE: Cook mushrooms briskly in butter until golden, then lower heat, stir in flour and cook 1 minute. Stir in milk and cream, season with salt and lemon juice and simmer 3 minutes. Stir in parsley.