Preheat oven to 350º F. Line a 9x13 inch pan with parchment paper or grease and flour pan. Set aside.
In a large bowl whisk together brown sugar, oil and vanilla until combined. It will be the texture of wet sand
Add flour, cocoa powder, salt, and baking soda. Mix until mostly combined. The mixture will be stiff and dry.
Add the zucchini and 3 Tablespoons of milk. Mix until it comes together as a batter. If the mixture is dry, let it rest for 5 minutes and stir again. If necessary, add additional 2 Tablespoons of milk.
Stir in ½ cup of chocolate chips.
Pour batter into prepared pan. Sprinkle the remaining chocolate chips over the top.
Bake for 28-32 minutes or until a tester comes out mainly clean. Be careful not to over bake.
Let cool completely before serving.
