Preheat oven to 350. In 2 1/2 quart saucepan over low heat, melt butter. Remove from heat. Add sugar, flour, cocoa, powder, salt, eggs & vanilla. Stir with spoon until batter is well blended & smooth.
Stir in 1 1/2 cups morsels & nuts. Spread into a 13 X 9" baking pan. Sprinkle with remaining morsels. Bake 30-35 minutes until set. Cool on wire rack. Cut into 2" squares.