Preheat your oven to 350°F (175°C) and prepare a 9x13-inch metal baking pan by greasing it and lining with parchment paper.

Melt 2 cups of semisweet chocolate chips and 1 stick of unsalted butter in a saucepan over medium-low heat, stirring until smooth. Remove from heat and cool for 15 minutes.

In a small bowl, whisk together 1 cup of all-purpose flour, 1/2 cup of cocoa powder, 1/2 teaspoon of baking powder, 1/2 teaspoon of baking soda, and 1/4 teaspoon of fine sea salt.

In a large mixing bowl, whisk together 3 eggs, 1.5 cups of sugar, 1/4 cup of vegetable oil, and 2 teaspoons of vanilla extract until frothy. Stir in the cooled chocolate mixture.

Gradually add the dry ingredients to the wet ingredients, mixing gently. Fold in 2 cups of shredded zucchini.

Pour the batter into the prepared pan and spread it evenly. Sprinkle with reserved chocolate chips.

Bake for 35-40 minutes. Check for doneness with a toothpick; it should come out with a few moist crumbs.

Cool in the pan for at least 20 minutes, then lift out using parchment paper, cut into squares, and serve warm.