Preheat an oven and prepare the loaf pan. Place a rack in the center of the oven, then preheat to 350 F. Coat a 9x5 loaf pan with baking spray, then line with parchment paper.
Mix the dry ingredients. In a large mixing bowl, whisk together 2 cups all-purpose flour, ¾ tsp ground cinnamon, ¾ tsp baking soda, ½ tsp baking powder, and ½ tsp Kosher salt.
Mix the wet ingredients. In a separate mixing bowl, whisk together ½ cup melted butter, ⅓ cup Greek yogurt, ⅔ cup brown sugar, ⅓ cup granulated sugar, 2 large eggs, and 2 tsp vanilla extract. Fold in the grated zucchini.
Fold together. Pour the dry ingredients on top of the wet ingredients, then use a rubber spatula to stir until just combined and only a few streaks of flour remain. Fold in 1 ¼ cup chocolate chips, gently mixing to combine.
Bake the zucchini bread. Pour the chocolate chip zucchini bread batter into the prepared loaf pan, then smooth the top with a spatula. Sprinkle on the remaining ¼ cup chocolate chips. Bake for 60 - 75 minutes, rotating the pan once halfway through baking, or until a toothpick or knife inserted into the center comes out clean.
Cool, then slice. Transfer the pan to a cooling rack, sprinkle with flaky sea salt (if using), then allow to cool for at least 30 minutes. Invert to remove from the loaf pan, then slice into 8 equal pieces then enjoy!