Weekend recipe: Tres Leches Cake!

Sarah made this (not our recipe) for a student of hers. I ate about half of it before it left the house.

Cake:

5 eggs, separated (meaning, put the yolks in one bowl, and the whites in another)
1/3 cup milk
1/2 tsp vanilla
1 c flour
1 1/2 tsp baking powder
1/2 tsp cream of tartar
1 c sugar

Syrup:

1 can evaporated milk
1 cup sweetened condensed milk
1 cup whipping cream
1 tsp vanilla
1 tsp dark rum

Do:
-Preheat oven to 350
-Beat yolks and 3/4c sugar until "light and fluffy", then beat in milk, vanilla, flour, and baking powder.
-Beat eggs whites until they're making peaks, beat a little more and add the cream of tartar.
-Mix in the remaining sugar, then mix the yolk and white mixtures together.
-Pour batter into a 13x9 pan (greased/buttered) and bake for 30 minutes, or until you can stick a chopstick in the middle and it comes out clean.

-Mix up all the syrup ingredients.
-Poke a ton of holes in the cake with a fork, then start dumping the syrup on it and brushing it around until it has all soaked in.
-Top with cocoa powder, or mango slices, or ice cream, or cinnamon, and consume!

-Beat