In a bowl, mix the milk, cornstarch and sugar. Place on the heat and mix well until the mixture thickens a little.
In another bowl, mix the yolks, vanilla sugar, egg and whites.

Add the oil, milk, flour and baking powder to the egg yolk mixture and mix well.
Pour half of the mixture into a previously buttered and floured mold.
Add a layer of apricot jam to the surface of the dough.

Pour the rest of the mixture over the jam, leveling gently.
Bake at 170°C for 30-40 minutes or until the cake is golden and a toothpick inserted in the center comes out clean.

Once cooked, let the cake cool before dusting it with icing sugar.