Source: Life in Recipes
Tres Leches Cake
3 eggs, separated
1/8 teaspoon cream off tartar
1 cup sugar
1 cup flour
2 teaspoons baking powder
1/4 cup milk
The Tres Leches (3 milks)
3/4 cup plus 2 tablespoons sweetened condensed milk
3/4 cup evaporated milk
1/2 cup heavy cream
Begin by greasing an 8-inch square baking dish and preheating your oven to 350F.Sift together your flour and baking powder.
Whisk your egg whites, along with the cream of tartar, until soft peaks from. Gradually add the sugar. Add the egg yolks, one at the time, until well incorporated. Add the flour mixture in 1/4 portions, mixing gently to combine before adding the next portion. Add 1/4 cup milk and stir to combine. Pour mixture into prepared cake pan and place on rack in middle of oven. Bake for 30 minutes, or until a skewer/toothpick inserted in middle of cake comes out clean.
Allow to cool in pan on a rack for 10 minutes.
While cake is resting, prepare the topping. Simply pour your three milks together into a measuring cup or pitcher and stir to combine.
With a skewer, poke holes all over cake in one-inch intervals. Run a knife around the sides of the pan to loosen the cake from the sides. Carefully pour the three-milk mixture over the cake, making sure you get all the way to the edges and down the sides of the cake. You may have to pause in your pouring to let the cake soak up the liquid before adding more. Don't worry, it will all fit - just be patient.
Cover the cake and place in the refrigerator for at least two hours or overnight. Serve with slightly sweetened whipped cream, or just plain. It is your cake and ice-cream in one package, after all.