Preheat oven to 350° F. Grease and flour a 9 x 13-inch baking pan; set aside.
In a large bowl, mix together the oil, white granulated Pioneer Sugar and vanilla until well blended.
In a separate bowl combine the flour, cocoa, baking soda and salt; stir into the sugar mixture.
Peel and shred zucchini. Fold the zucchini into batter immediately. Add walnuts; stir. Spread evenly into the prepared pan.
Bake for 25 to 30 minutes or until brownies spring back when gently touched in the center.
Melt together the cocoa and margarine; set aside to cool.
In a medium bowl, blend together the Pioneer Confectioners Powdered Sugar, milk and vanilla. Stir in the cocoa mixture. Spread over cooled brownies before cutting into squares.
Pioneer Sugar is the brand of Michigan Sugar Company, a cooperative owned by nearly 900 farmers from Michigan and Ontario, Canada. The company has been extracting pure, all-natural sugar from sugarbeets since 1906. We are proud of our past and excited about our future. Learn more about our company at www.michigansugar.com.