Preheat an oven to 180 degrees C. Lightly butter a 33cm x 23cm oblong cake tin.
Whisk together 1 1/2 cup flour and icing sugar in a mixing bowl. Cut in the cold butter with a knife or pastry blender until the mixture resembles coarse crumbs. Press the crumbs into the bottom and up the sides of the prepared baking dish to form a base.
Bake in the preheated oven until golden brown, 15 to 18 minutes. Remove from oven and set aside.
Whisk together 4 eggs, 1 1/2 cup sugar, 1 tablespoon flour, lemon zest and lemon juice in a bowl. Pour lemon mixture into the prepared base. Skim off any bubbles from the surface of the filling. Mix the cream cheese and 1 cup sugar in a bowl until well blended. Whisk in 2 eggs then spread over the lemon mixture. The mixtures will separate during baking.
Bake in the preheated oven until the filling is set, about 30 minutes.