Preheat oven to 375°F
Line at least the bottom of a 10x15 inch jellyroll pan with parchment paper
Get the second and third large mixing bowls (one of which should be glass)
Crack the 6 eggs and separate the whites into the glass bowl and the yolks into the other one.(If they're both glass and different sizes, put the whites in the larger one.) 6 eggs
Add sugar to the yolks
4 oz normal, granulated sugar
Use the electric mixer to beat them until thick and pale yellow, but still liquidy -- a couple of minutes on high
Add in the salt and the second portions of cocoa and vanilla
1 oz more unsweetened cocoa powder, 1-½ tsp more vanilla extract, 1/8 tsp salt
Blend with the mixer until the ingredients are well incorporated
Clean the mixer's beaters again
In the large glass bowl, whip egg whites to soft peaks, a couple of minutes on high
While still whipping, gradually add more sugar, and continue whipping until the mixture forms stiff peaks and mixer's tracks remain, another couple of minutes on high
2 oz more granulated sugar
Fold the yolk mixture into the whites and mix with the spatula until well mixed
Spread the batter somewhat evenly into the prepared pan, on the parchment -- uneven parchment paper can trick you, around corners and ends