Cocoa Brownies

2 c. sugar
1 1/2 c. flour
3/4 c. cocoa
1 t. salt
1/2 c. butter
1/2 c. shortening
3 eggs
2 t. vanilla
1 c. chocolate chips
1 c. chopped nuts, optional

Preheat oven to 350 F. Beat sugar, flour, cocoa, salt, butter, shortening, eggs and vanilla for 3 minutes, then add chips and nuts. Grease and flour 9x12 pan. Bake 30 minutes.