Preheat oven to 350 degrees F. Butter or spray and flour a 9 X 13 inch glass or non-stick baking pan.
Melt unsweetened chocolate and butter in a large saucepan over medium heat. Do not burn. Remove from heat. Using a wooden spoon or spatula, add sugar and stir until well mixed. Add eggs, vanilla and salt and beat well with a wooden spoon.
Fold in flour and mix just until smooth. Do not over mix. This is also the time to fold in chopped nuts & chocolate chips.
Pour into prepared pan. Bake at 350 degrees for 30-40 minutes or until knife comes out clean.
GARNISH: Cool for about 15 minutes, then spread desired amount of Nutella over warm brownies (optional). If desired sprinkle with nuts and chocolate chips on top. (Cool completely before cutting into squares.)