Preheat oven to 350℉. In a medium bowl, whisk together the flour, salt and baking powder. Set aside.
In a large mixing bowl, use a wire whisk to beat together the egg yolks, ¼ cup sugar, milk and vanilla extract until everything is incorporated and the mixture is a bit frothy.
Add the dry mixture to the wet mixture in two additions. Beat to incorporate, but just until the mixture is smooth.
Beat the egg whites in the bowl of a stand mixer until frothy. Add the cream of tartar and continue to beat until soft peaks form. Then with the mixer still running, gradually add the remaining ¼ cup sugar until the egg whites form stiff peaks.
Gradually fold the beaten egg whites into the yolk batter using a rubber spatula, until the mixture is uniform in color. Be gentle so as not to deflate the volume. Pour and scrape the batter into a 9x 13 inch baking pan.
Bake at 350℉ for 25-30 minutes, or until the cake springs back to the touch and is lightly browned. Place the cake pan on top of a wire rack to let it cool completely.
Meanwhile, make the milk mixture, Stir together condensed milk, evaporated milk and whipping cream very well until combined. Make sure the condensed milk is incorporated well as it is quite thick.
Once the cake is cool, poke holes all over the surface using the tines of a fork. Make sure the holes are all over the cake and not just random. Slowly pour the milk mixture all over the cake, stopping once the liquid pools in the surface. Allow the liquid to soak the cake completely. Once the surface the liquid is almost soaked up, start pouring more. Repeat until the milk mixture is all used up. Tip: It helps to tilt the pan to distribute the liquid along the sides of the cake too.
Spread the whipped cream all over the cake. Top with desired toppings.