Preheat your oven to 350°F (175°C). This ensures that your cake bakes evenly.
Grease your 9x13-inch baking pan with a bit of olive oil or line it with parchment paper for easy removal.
Using a grater, finely grate the zucchini. You can leave the skin on for added nutrients and color.
In a large mixing bowl, whisk together the gluten-free flour, dark brown sugar, cocoa powder, baking soda, baking powder, and kosher salt until well combined.
In another bowl, combine the lightly beaten eggs and olive oil. Whisk until fully blended.
Add the wet ingredients to the dry ingredients, mixing just until combined. Do not overmix.
Gently fold in the grated zucchini and date crumbles until evenly distributed throughout the batter.
Pour the batter into the prepared baking pan, spreading it evenly.
Bake in the preheated oven for 35-40 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cake to cool in the pan for about 10 minutes before transferring it to a cooling rack. Once cooled, slice and serve.