Preheat oven to 350°. Grease and flour a 13x9x2" cake pan.
For the cake, in a bowl, beat 8 egg whites at high speed with an electric mixer until stiff peaks form. Add 8 egg yolks and continue beating until fully incorporated. With the mixer running, gradually add 1 cup of sugar.
With a spatula, gently fold the flour into the egg mixure. Be sure the flour is completely incorporated. Transfer batter into the prepared cake pan, smoothing the top to level.
Bake until a wooden toothpick inserted into the center of the cake comes out clean. Approximately, 20 minutes. Start checking cake at 20 minutes and repeat test every 3-minutes until cake is done. *See note #1.
While cake is baking, in another bowl, combine 2 cups of heavy cream, condensed milk, and evaporated milk, stirring well to blend. Set aside.
When cake is finished baking, remove from the oven and let sit 10-minutes. Gently ladle the combined milks over the hot cake. It may look like too much milk, but as it sits it will absorb all of it. Let the cake cool, then cover and refrigerate a minimum of 4 hours, but preferably overnight. *See note #2.
For the sabayon, whip one cup of heavy whipping cream until it forms stiff peaks. Set aside.
For the sabayon, prepare an ice bath. Place about 8 cups of ice cubes in the bottom of a large bowl. Add about a quart of water. This is necessary to quickly cool the sabayon sauce after it is pulled from the stove top. Set aside.
For the sabayon, combine 4 egg yolks, 1/2 cup sugar and 1/4 cup orange juice (*see note #3) in the top of a double boiler over simmering water. I use a metal or glass bowl over a small pan (nothing fancy). Do not let the bowl touch the simmering water. You're just allowing it to steam the bottom in order to cook the egg yolks while you whisk. If it comes into contact with the bottom of the bowl you run the risk of scrambling the eggs. Whisk continuously until the sabayon becomes lightened in color, thick and falls in ribbons from the whisk. Approximately 12-15 minutes.
Move the bowl with the sabayon to the ice bath and continue to whisk. The sabayon will continue to lighten in color and thicken even further. Gently fold the whipped cream into the sabayon in thirds until well incorporated. Sabayon will be very silky and almost frothy. Refrigerate until ready to serve. Can be made a day ahead.
For the berries (*see note #4), 1 hour before serving, wash and slice the berries, toss with sugar and squeeze the juice of half a lemon over the top. Stir to combine and set aside until ready to serve.
To serve, slice cake and layer with berries. Top with sabayon sauce.