Preheat your fan-forced oven to 180°C (fan forced) 350°F. Grease and line a 20-23cm springform tin.
In a medium bowl, rub sugar and lemon zest together with your fingers to enhance the citrus oils. Mix in the cooled melted butter, then add salt and lemon juice. Stir in the egg, mix again, then add the baking powder and gradually incorporate the flour, whisking until smooth.
Spread the mixture into a lined springform tin and set aside.
In a new bowl, combine cream cheese, lemon zest, lemon juice and sugar until smooth.
Pour the creamy mixture over the base and bake at 180°C (fan forced) 350°F for 45 minutes.
Let it cool completely before removing from the tin, then dust with icing sugar before serving.
