Combine chocolate and butter in top of a double boiler; place over simmering water, and cook, stirring constantly, until mixture melts. Remove from heat, and cool.
Stir in sugar; add eggs, one at a time, beating well after each addition. Add vanilla, and stir until well blended.
Combine flour, salt, and pecans in a small mixing bowl; stir to coat well. Gradually add to chocolate mixture, stirring well after each addition.
Spread mixture evenly in a greased and floured 15- x 10- x 1-inch jellyroll pan. Bake at 325° for 30 minutes. Remove from oven, and cool completely in pan. Spread frosting evenly over brownies, and allow to set before cutting into 2-inch squares.