Begin by placing the butter in a large microwave-safe bowl and melt it in the microwave until fully liquefied and hot. Add the chocolate chips, heating them for another 20 seconds before allowing the heat to melt them completely. Let it sit for a few minutes and then stir until smooth. If any pieces remain unmelted, briefly reheat and stir again. Alternatively, you can use a small saucepan on the stove for this step.

Next, whisk in the cocoa powder and sugar directly into the warm, melted chocolate mixture. There's no need to let it cool down beforehand. Preheat your oven to 375°F (190°C) or 350°F (175°C) for fan-assisted ovens. Prepare an 8x8-inch (20x20 cm) baking pan by lining it with parchment paper. If you prefer a thinner cake, a 9x13-inch (23x33 cm) pan can be used, but the height of the cake will be reduced.

Grate the zucchini finely and immediately stir it into the chocolate mixture. Once incorporated, add the eggs and salt, and if desired, a pinch of cinnamon. Whisk together until the mixture is smooth and fully blended.

Gently fold in the flour and baking powder, mixing until just combined. Take care not to overmix, as this can result in a denser texture. Pour the batter into the lined pan, smoothing it evenly with a spatula for a uniform finish. Bake for 17 to 20 minutes, keeping a close eye on it toward the end. The cake is done when a toothpick inserted in the center comes out clean. Avoid overbaking, as this will cause the cake to dry out. For the best texture, remove it from the oven as soon as it's fully baked.

Serve the cake warm, either dusted with powdered sugar or plain. If you'd like to add ganache, allow the cake to cool completely before proceeding.

Melt the butter in a small saucepan over medium heat until hot. Lower the heat and add the chopped chocolate, stirring gently to melt it. Keep the temperature low to avoid overheating the chocolate, which can cause it to seize. If needed, remove the pan from the heat to control the melting process.

Once smooth, pour the warm ganache over the cooled cake. It will be thin and easy to spread at first, but will thicken as it cools. The ganache will set in about an hour, but you can speed up this process by refrigerating the cake.