Zucchini Brownies

INGREDIENTS

• 1/2 cup vegetable oil
• 1 1/2 cups white sugar
• 2 teaspoons vanilla extract
• 2 cups all-purpose flour
• 1/2 cup unsweetened cocoa powder
• 1 1/2 teaspoons baking soda
• 1 teaspoon salt
• 2 cups shredded zucchini
• 1/2 cup chopped walnuts
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• 6 tablespoons unsweetened cocoa powder
• 1/4 cup margarine
• 2 cups confectioners' sugar
• 1/4 cup milk
• 1/2 teaspoon vanilla extract