Preheat an oven to 175℃ / 350 ℉
In 2 large bowls, separate your eggs placing the whites in one bowl and the yolks in the other.
Next, add half of the sugar into the egg yolks and the other half into the egg whites. Set the egg whites to one side.
Add the vanilla and salt into the egg yolks and whip until light and fluffy. The egg yolk mixture should be a pale yellow color.
Next, pour the buttermilk into the egg yolks and gently fold, until well mixed.
Sift the flour and baking powder into the yolks and softly fold until fully combined and there are no streaks of flour left. Then, set this mixture aside.
Now, start whipping the egg whites until super light and fluffy. The egg whites should be able to hold a stiff peak and be completely white in color.
Add ¼ of the egg whites into the egg yolk mixture and gently fold, making sure not to lose too much air.
Then, VERY GENTLY fold in the egg yolks into the rest of the egg whites until fully combined.
Finally, pour the cake batter into an ungreased baking pan and smooth it into an even layer. Bake for 25 to 30 minutes, or until a toothpick inserted in the centre of the cake comes out clean. Remove from the oven and allow the cake to cool completely.
For the milk mixture, simply combine the evaporated, condensed and whole milk in a bowl, with the vanilla. Mix well, until fully combined.
Once the cake is fully cooled, poke all over with a fork and pour over your three milk mixture. Make sure you get all the sides and that there are no dry spots on the cake.
Place the cake into the refrigerator and allow to soak for at least 4 hours or ideally overnight.
Finally, whip together the double cream, icing sugar and vanilla, until light and fluffy. And top the cake with the whipped cream and smooth into an even layer. Then decorate as you wish, slice and enjoy!