6 oz. bittersweet chocolate
1 oz. unsweetened chocolate
1/4 lb. (1 stick) butter
4 eggs at room temperature
1 tsp. vanilla
1/4 tsp. salt
1-1/2 cups white sugar
1 cup white flour
1 cup chopped walnuts or pecans (optional)
Melt the butter and chocolate together. (Microwave in a four cup glass measure 1 minute at a time on high and stirring between each 1 minute session or in a double boiler.) Let cool for a full hour. The chocolate has to be cool and the eggs warm to get the right texture.
Measure out all the other ingredients. Grease a 9x12 metal baking pan. (I wouldn't try this with a clear glass baking pan.)
Preheat the oven to 350°. Break the eggs into a two-quart or larger mixing bowl. Add the salt. Beat the eggs for a full 7 minutes with your electric mixer on high.
At the end of 7 minutes, your eggs should be a pale yellow color, and fill about 2/3rds of the bowl. Add the vanilla and keep beating.
Add the sugar one tablespoon at a time. By the time you're down to the last 1/4 cup or so of sugar, the mixture should be thick and have a tendency to climb up the mixer.
Stir the cool chocolate mixture well and pour it on top of the eggs. “Fold” the ingredients together. (To fold, slide the spatula from the edge of the bowl towards the bottom, then up in a circular motion.) Fold until the batter is streaked with chocolate but not entirely mixed. Shake half the flour in a thin layer over the top of the bowl, and start folding again. When you can't see much flour, add the other half in the same way. As soon as most of the flour is incorporated, add the nuts and fold just a little more until the mixture is evenly colored. Pour into the greased pan, smooth it out pretty evenly, and put into the oven for exactly 25 minutes. Let the brownies cool completely in the pan before cutting.