In a small saucepan melt the chocolate and the butter over low heat, stirring until the mixture is smooth, and let the mixture cool completely. In a large bowl with an electric mixer beat 2 of the eggs, add 1 cup of the sugar, a little at a time, beating, and continue to beat the mixture at high speed for 3 minutes, or until it is thick and pale. Beat in the remaining 2 eggs and the remaining 1 cup sugar, a little at a time, and beat the mixture for 5 minutes, or until it is very thick and pale. Stir in the chocolate mixture and the vanilla, add the flour and the salt, stirring until the mixture is blended well, and stir in the walnuts. Pour the batter into a buttered and floured baking pan, 1 3 by 9 by 2 inches, smoothing the top, and bake it in the middle of a preheated 350 ° F. oven for 35 to 40 minutes, or until it pulls away slightly from the sides of the pan and a wooden pick inserted in the center comes out with crumbs adhering to it. Transfer the pan immediately to a rack set on the bottom shelf of the refrigerator and chill the brownies for 1 to 2 hours, or until they are cooled completely, before cutting them into serving pieces. COOK 034