Melt chocolate and shortening in double boiler. Remove top part from hot water and blend in sugar, then eggs. Add flour and salt; Stir well with a spoon. Add vanilla*. Pour into 2 greased or oiled 8x8x2-inch baking pans;spread smooth and sprinkle with nuts. Bake in moderately hot oven of 400 degrees F. for 12 minutes. Cool. Cut into 2-inch squares. Makes about 52 squares.