Heat the oven to 350°F. Lightly grease a 9x5 loaf pan and line it with parchment paper, leaving some overhang on the long sides so the finished loaf is easy to lift out.

Grate the zucchini on the large holes of a box grater, measure out 1 1/2 cups (270g), then squeeze out the excess liquid with your hands over the kitchen sink. Set the drained zucchini aside.

In a medium bowl, whisk the all-purpose flour, baking soda, baking powder, and kosher salt until well combined. Set aside.

In a large bowl, whisk the cooled melted butter, granulated sugar, and brown sugar until smooth. Add the sour cream, eggs, vanilla, and the squeezed zucchini, and stir until fully incorporated.

Pour the dry ingredients into the wet mixture and fold gently with a rubber spatula until the flour is just moistened.

When a few streaks of flour are still visible, fold in the dark chocolate chips until evenly distributed without overmixing.

Scrape the batter into the prepared pan and smooth the top. Sprinkle a little extra chocolate over the surface, then bake for 60 to 70 minutes or until a toothpick inserted in the center comes out mostly clean.

Move the pan to a wire rack and let the bread cool in the pan for 30 to 40 minutes. Use the parchment overhang to lift the loaf out and let it cool completely on the rack if time allows.

Sprinkle flaky sea salt over the top, slice, and serve.