Break the macaroni into 1/2-in lengths and throw into boiling, salted water.
Cook for 10 min until just tender.
Strain the macaroni and put it into the saucepan with the milk and simmer until quite soft.
Add the sugar, lemon rind and butter.
Separate the eggs and stir in the beaten yolks, stir for a few minutes but do not let it boil.
Whip the egg whites stiffly and fold lightly into the mixture.
Remove the lemon rind.
Pour into a buttered pie-dish and cook until brown in a moderate oven (350° F., Gas 4)—about 20-30 min.