Melt butter in sauce pan. When melted remove from heat. Add cocoa and stir well. Add sugar, eggs and vanilla. Mix until shiny and smooth. Add flour, baking powder and salt. Mix well. Add choc chips or walnuts if desired.
Pour into an 8 inch or 9 inch pan. Bake for 15-20 miutes. Do not over bake. Look for edges slightly pulling away from pan. Cool and cut. Enjoy!