01 -
Preheat oven to 350°F (175°C). Grease and flour a 9x13-inch baking pan, ensuring complete coverage to prevent sticking.
02 -
In a large bowl, mix sugar, vegetable oil, and 2 teaspoons vanilla extract together until well blended and smooth.
03 -
In a separate bowl, whisk together flour, ½ cup cocoa powder, baking soda, and salt until evenly distributed. Gradually stir dry mixture into the wet ingredients until just combined.
04 -
Gently fold in shredded zucchini and chopped walnuts until evenly distributed. Spread batter evenly into the prepared baking pan.
05 -
Bake for 25 to 30 minutes until the top is dry and edges begin to pull away from the sides. Cool completely in pan for about 20 minutes.
06 -
While brownies cool, whisk 6 tablespoons cocoa powder and butter in a small saucepan over medium-low heat until smooth and glossy. Set aside to cool.
07 -
Blend confectioners' sugar, milk, and ½ teaspoon vanilla extract together. Stir into the cooled cocoa mixture until smooth. Spread evenly over cooled brownies before cutting into squares.