The tres leches in the title refer to the condensed milk, evaporated milk, and heavy cream that go into the delcious syrup used to soak this rich cake. This recipe is reproduced with permission from iCuban.com.
2 cups all-purpose flour
1 1/2 tsp. baking powder
9 eggs, separated
1 tsp. cream of tartar
1 1/2 cups sugar
12 tablespoons (1 1/2 sticks) butter, at room temperature
1 tsp. vanilla extract
1 cup whole milk
1 cup sweetened condensed milk
1 cup evaporated milk
1 cup heavy cream
1 tbsp. light rum
6 egg whites
Pinch of salt
1/4 tsp. cream of tartar
1 1/2 cups sugar
1. Make the cake: Preheat the oven to 350°F. Lightly butter a 9 x 13-inch baking pan.
2. Sift together flour and baking powder. In a bowl, with an electric mixer, beat egg whites and cream of tartar until stiff peaks form. Set aside.
3. In another bowl, cream sugar and butter. Beat in yolks and vanilla. Beat until fluffy. Continue mixing, adding flour mixture and whole milk alternately, until batter is smooth. Gently fold in beaten egg whites with spatula.
4. Pour batter into the baking pan and bake for 25 to 30 minutes, or until a toothpick inserted in the center comes out clean. Let cake to cool on rack 20 minutes, then invert onto serving plate. Pierce top of cake repeatedly with a fork.
5. Make the milk syrup: In a bowl, whisk together milks, cream, and rum. Pour syrup over cake a little at a time, until cake is soaked through. Cover cake in plastic wrap and refrigerate at least 3 hours.
6. Make the frosting: In a bowl, with an elecric mixer, beat egg whites with salt and cream of tartar until they form stiff peaks.
7. In a medium saucepan, combine sugar and 3/4 cup water. Cook over medium-high heat until candy thermometer reads 230°F. Remove from heat. Pour egg white mixture into pan, rapidly mixing by hand about 5 minutes or until firm. With wet spatula, spread thick layer of frosting over top and sides of cake.