Preheat the oven to 150'C.
Have the butter and cream cheese at room temperature before starting this recipe.
Place a heatproof bowl over a pan of simmering water and add the milk, warm it gently and then add the cream cheese. Mix well and then stir in the butter.
Remove from the heat and allow the mixture to cool a little.
While it cools zest the lemon and separate the eggs into two bowls.
Whisk the egg yolks into the cooled mix, add the lemon zest and then sift in the plain flour and corn flour. Fold gently until the flours are completely combined.
Whisk the egg whites until they turn white, add the cream of tartar and then the caster sugar in a steady stream while you whisk the mixture to stiff peaks.
Fold the egg white mix very gently into the cream cheese mix. Pour into a baking tray lined with parchment paper and then put this tray into a larger tray half filled with water (a bain marie). Cook for 50 minutes, if a skewer comes out clean it is cooked.
Allow to cool and then slice and serve.
«You can also make this recipe in small ramekins, reduce the cooking time to 20 minutes, cool them in the ramekin and then top with sliced fresh fruit.»