1. For the crust Mix altogether the dry ingredients. Then rub in butter and after that the egg to make a smooth dough.
2.Roll the dough 1/4 inch thickness and place in a loose bottom cake tin , ( make you place a grease-proof paper at the bottom of the cake tin. Press dough firmly at the side too about 2 inches height. Leave to chill while you make the the filling.
3. Whisk egg white till stiff and leave aside,in a small bowl mix evapourated milk with lime juice, keep aside till it curds.
4. In another bowl, add cream cheese and yolk, beat till smooth, add sugar, the milk curd, zest and flour, beat till smooth. Then fold in the egg whites slowly with a metal spoon.
5. Pour cheese batter into crust shell leaving about an inch space at the crust. It will rise when it bake.
6. bake in a preheated oven at 220 C for 20 mins and lower heat to 200 C and continue baking for another 25 mins or till firm .leave the cake cool in the oven by just opening the oven door.
7. when cool, chill cake before cutting.
you can pipe your fav whipped cream on top if you like by creaming the whipped cream with a little lime juice and zest.