Preheat the oven to 180 'C and line a 8 inch springform pan. In a mixing bowl combine sugar, flour and salt. Stir in orange zest, orange juice and butter. In another bowl beat in egg yolks thoroughly with a beater, beat in cream cheese and milk.. Fold into the orange mixture. Beat egg whites till stiff peaks forms and fold to the batter. Pour batter into biscuit base. Place baking pan on a large tray and pour hot water into larger tray to a depth on 1 inch. This will help to bake a moist orange cheese cake. Bake for 45 minutes or until done.
Bake in the 180 ‘C oven for about 40 minutes or till set.