Place oven rack in center and preheat to 350 degrees F.

Sift the flour and salt together and set aside.

Melt the butter and chocolate together in a medium saucepan over very low heat, stirring constantly, keeping a watchful eye on it ensuring the chocolate doesn't scorch (a double boiler is ideal). Add 1 cup of the sugar and stir for 30 seconds, then remove pan from heat and stir in vanilla. Pour this mixture into a large bowl.

Pour in remaining cup of sugar and the eggs into your mixing bowl (you can do this by hand-held mixer, too) and whisk by hand just to combine. SLOWLY pour half of the sugar and eggs into the chocolate mixture, stirring gently but constantly with a rubber spatula so that the eggs do not set from the heat.
Whip the remaining sugar and eggs in their seperate bowl until it's thick, pale, doubled in volume (about 3 minutes). Using your spatula, gently fold the whipped eggs into chocolate mixture. When eggs are almost completely incorporated, gently fold in the flour and salt.

Pour and scrape the batter into an ungreased 9" square pan- a heavy ceramic or glass pan is ideal. Bake for 25-28 minutes, during which time they will rise a little and top will turn dry. Cut into the center at the 23 minute mark to check progress: They are perfect when barely set and still gooey. Let cool in the pan on a wire rack

If cut into 1 1/2"x3" bars will yield 18 brownies.