Tres leches is a moist and dense cake from Latin America that is soaked with a mixture of three milks -- sweetened condensed milk, evaporated milk and heavy cream.
Preheat oven to 350°F. Mix flour, cinnamon and salt in small bowl. Set aside. Beat egg yolks and 3/4 cup of the sugar in large bowl with electric mixer on high speed 5 minutes or until light and fluffy and doubled in volume, scraping sides of bowl occasionally. Gradually beat in 1/2 of the flour mixture, 1/4 cup of the milk, 2 teaspoons of the vanilla, then remaining flour mixture on low speed until well blended, scraping sides of bowl occasionally.
Beat egg whites in clean large bowl with electric mixer on high speed 2 minutes or until soft peaks form. Gradually beat in 1/4 cup of the remaining sugar until stiff peaks form. Stir 1/3 of the egg white mixture into the batter until well blended. Gently stir or fold in remaining egg white mixture. Pour evenly into greased 13x9-inch baking pan.
Bake 25 to 30 minutes or until toothpick inserted in center comes out clean. Cool in pan on wire rack 5 minutes. Meanwhile, mix remaining 1/2 cup milk, sweetened condensed milk and evaporated milk in medium bowl until well blended. Poke holes in warm cake with kitchen fork at 1-inch intervals, moving fork side to side to enlarge holes slightly. Pour milk mixture slowly over cake. (Milk mixture will be slowly absorbed by the cake.) Cool completely. Cover.
Refrigerate at least 3 hours or overnight for best results. Beat cream, remaining 2 tablespoons sugar and remaining 1 teaspoon vanilla in medium bowl with electric mixer on high speed until stiff peaks form. Frost cake with whipped cream. Refrigerate until ready to serve.