Heat oven to 350 degrees. Grease 13 x 9 x 2-inch baking pan or two 8-inch square baking pans. In large bowl, stir together cocoa and baking soda; stir in 1/3 cup butter. Add boiling water, stir until mixture thickens. Stir in sugar, eggs, and remaining 1/3 cup butter; stir until smooth. Add flour, vanilla and salt; blend completely. Stir in chocolate chips. Pour into prepared pan. Bake 35 to 40 minutes for rectangular pan, 30 to 35 minutes for square pans or until brownies begin to pull away from sides of pan. Cool completely in pan on wire rack. Frost with Buttercream Frosting. Cut into squares.
6 Tablespoons butter or margarine, softened
2 2/3 cups powdered sugar
1/2 cup Hershey's Cocoa
1/3 cup milk
1 tsp. vanilla extract
In small mixer bowl, beat butter. Add powdered sugar and cocoa alternately with milk; beat to spreading consistency (additional milk may be needed). Blend in vanilla. Makes 2 cups frosting.