Preheat oven to 150°C. Line the base and sides of a 20cm springform cake tin with baking paper. The baking paper on the sides need to be at least 10cm in height.
Cover the bottom of the cake tin with foil so that water won’t get into the cake tin, and place the cake tin in a roasting pan.
Heat Milk and Butter in a saucepan until Butter is melt.
Combine Flour and Corn Starch in a large bowl. Add the hot Milk & Butter mixture and use a whisk to mix well. Add Egg Yolks and Vanilla, and mix well.
In a separate bowl, beat Egg Whites, using an electric mixer, until soft peaks form. Gradually add Caster Sugar, beating well, until thick and glossy and Sugar is well dissolved. Gradually fold in the Egg White into the mixture and gently combine well.
Pour the mixture into the prepared cake tin. Pour boiling water into the roasting pan. Bake for 60 minutes or until cooked through.
Take out to a wire rack to cool, or enjoy it while it is still warm.
