Combine sugar, flour, and salt in a medium mixing bowl; mix well, and set aside.
Melt chocolate and butter over hot water in top of a double boiler, stirring veil. Gradually stir chocolate mixture into flour mixture. Stir in eggs, vanilla, and chopped pecans.
Pour batter into a greased 13- x 9- x 2-inch baking pan. Bake at 325° for 40 to 45 minutes or until a wooden pick inserted in center comes out clean. Cool. Cut into squares to serve.