Preheat oven to 190 C / 375 degree F / Gas Mark 5.
Mix the ready-made sponge mix with 140ml of water and 1/4 tbsp of salt, blend for 1 minuet on medium speed, then scrape bowl down, before blending for a further 4 minuets on medium speed.
Beat in the vanilla extract.
Gently fold in the evaporated milk & sugar (sugar is optional as the mix is already sweetened)
Pour batter evenly into 2 well greased and floured 9 inch cake pans.
Bake in oven at 190 C / 375 degree F / Gas Mark 5 for about 25-30 minutes or until a toothpick inserted in the center comes out clean. Watch it carefully, you will not want to over bake this cake, as soon as the toothpick comes out clean, remove the cake from the oven and let it rest in the pans for 5 minutes before turning it out onto a wire rack to cool completely.