Combine shortening and chocolate in top of a double boiler; place over simmering water, and cook, stirring constantly, until mixture melts.
Remove from heat, and add sugar, mixing well. Add eggs and vanilla; beat until well blended. Gradually add flour and salt, stirring well after each addition. Fold in 1 cup pecans.
Spread batter evenly in a well-greased 13- x 9- x 2-inch baking pan. Bake at 400° for 20 minutes. Cool completely in pan.
Spread frosting evenly over surface of brownies, and sprinkle with finely chopped pecans, if desired. Allow frosting to set before cutting brownies into 3- x 2-inch bars or assorted shapes.