Preheat your oven to 350°F. Line a 9x9 baking pan with foil and lightly spray with nonstick cooking spray.

In a medium saucepan over medium-low heat, combine the oil, chocolate chips, and cocoa. Whisk occasionally until the chocolate chips melt and the mixture is smooth. Take off the heat and whisk in the sugar.

Add the egg, egg yolk, and vanilla to the chocolate mixture, stirring until well combined. Mix in the grated zucchini.

Fold in the flour, baking soda, and salt until the batter is just combined. Don't over mix.

Spread the batter evenly in the prepared pan and bake for 20-25 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs.

While the brownies are baking, melt the butter, cocoa, chocolate chips, and milk together in a small saucepan over low heat. Remove from the heat and whisk in the vanilla and powdered sugar until smooth.

Once the brownies are out of the oven, pour the frosting over the top and spread it evenly. Let cool for 5-10 minutes, then lift the brownies out of the pan using the foil. Cut into pieces and enjoy