Steps

1. Preheat oven to 350 °F. Butter and flour a 10-inch cake pan.
2. Clarify the butter, and let cool.
3. Separate the eggs.
4. Beat the egg whites and salt together in a clean (grease-free) bowl with clean beater blades. Beat until soft peaks form, then sprinkle on the 2 tbs sugar and beat until stiff peaks form.
5. Beat the egg yolks, and while beating gradually add the 2/3 cup sugar. Add the vanilla extract, then continue to beat until the mixture is thick, pale yellow, and forms a ribbon, about 5 minutes.
6. Add 1/4 of the egg white mixture to the egg yolk mixture, and sift on 1/4 of the flour. Fold gently together until partly blended.
7. Repeat with another 1/4 of the total egg whites and flour, then another 1/4, and finally the remainder. With the last batch, add the butter. Mix well but gently to avoid deflating.
8. Spread evenly into pan. Bake 30 to 35 minutes, or 12 minutes for a jelly roll cake.
9. Invert onto a rack, then immediately flip again onto its base to cool.