Combine cornflour and custard powder with sugar in a saucepan. Gradually stir in water, stir until mixture is smooth. Add lemon rind and undrained can of pineapple. Stir constantly over medium heat until mixture starts to boil. Continue stirring, reduce heat slightly, boil 2 minutes. Remove from heat, quickly stir in butter and egg yolks. Mix well. Allow mixture to cool to room temp.

Cush biscuits finely. Do this with a rolling pin, or in a blender or food processor. Biscuits must be crushed finely and evenly. Any large pieces of biscuits will cause the crumb crust to break when cut. It is a good idea to push crumbs through a fine sieve after crushing if you don't have a food processor. Melt butter, add to crumbs, mix well with fork, press crumbs evenly over side and base of 23cm flan tin. Use a glass or cup to press crumbs firmly and evenly on to side of tin. Refrigerate the crumb crust while the pineapple filling is cooling.

Spread filling evenly into crumb crust, top with meringue, spreading it to edge of crust to form a seal.

Beat egg whites until soft peaks form, gradually add sugar, beat until dissolved. Bake in moderate over 5 to 10 minutes, or until surface of meringue is lightly browned.