Preheat
oven to gas mark 4/180º C. Mash cooked spinach by putting it
through a sieve. Beat yolks, salt, pepper and flour. Pour
milk into a saucepan and bring to boil. Pour in yolk mixture
and stir until thick.
Remove
from heat, add butter, spinach and cheese. Set aside to
cool. Beat egg whites until they become slightly frothy. Add
cream of tartar and continue to beat until stiff and dry.
Fold
spinach mixture into whites very lightly, pour into buttered
soufflé dish and bake immediately for 35 – 40 minutes.
Serve
immediately.
Any
delay in serving will cause the soufflé to collapse.
