Place cereal in a resealable plastic bag; seal bag. Using a rolling pin, roll over bag to crush cereal lightly. Mix crushed cereal, condensed milk, evaporated milk and 1/2 cup whole milk in large bowl. Refrigerate until ready to use.
Preheat oven to 350°F. Mix flour 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, remaining 1/4 cup milk, 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 remaining 1/4 cup 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. 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. Frost cake with whipped topping or Vanilla Whipped Cream. Sprinkle with additional cereal, if desired. Refrigerate until ready to serve.