Preheat the oven to 350.
Grease a 9x13" casserole pan with butter.Set aside.
In a large bowl, whisk together the flour, baking powder and salt.
Separate egg whites and yolks into two bowls.
Beat egg yolks with 3/4 cup sugar on high speed using hand mixer about 2 minutes (until yolks turn pale).
Stir in the milk and vanilla. Set aside.
Beat egg whites on high speed until soft peaks form (about 1 minute).
While continuing to beat, add in 1/4 cup sugar and beat until stiff peaks form (about another minute).
Use a spatula to add egg yolk mixture to the flour mixture and combine.
Add stiffened egg whites to this batter and fold in until just combined.
Pour batter into prepared pan and spread to level.
Bake at 350 for 30-35 minutes until a toothpick inserted in the center comes out clean.
Allow to cool.
In a bowl or large measuring cup, combine 1/3 cup heavy whipping cream, evaporated milk and condensed milk.
Stir until blended.
When the cake has cooled, use a fork to poke holes across the whole top of the cake.
Slowly pour milk mixture evenly over the cake.
In a large bowl combine remaining 2 cups cold heavy whipping cream and remaining 2 tbsp sugar and beat on high until thickened (about 2 minutes).
Spread over the cake and garnish whith berries if desired.
Allow to refrigerate at least 1-2 hours.