Prep the Zucchini. Grate the zucchini using the fine side of a box grater. Lightly squeeze out the excess water with your hands or a towel, but don’t overdo it. You want some moisture left for a soft texture.
Mix the Dry Ingredients. In a large bowl, whisk together the almond flour, cocoa powder, sweetener, baking powder, and salt until well combined and lump-free.
Add Wet Ingredients. Stir in the eggs, melted coconut oil (or butter), and vanilla extract. Mix until you get a smooth batter.
Fold in Zucchini and Chocolate Chips. Gently fold the grated zucchini and chocolate chips (if using) into the batter. It might look thick at first, but the zucchini will release moisture as it bakes.
Bake to Perfection. Pour the batter into a greased 8x8 inch pan and smooth the top. Bake at 350°F for 30–35 minutes, or until a toothpick inserted in the center comes out mostly clean. A few moist crumbs are okay.
Cool and Slice. Let the cake cool in the pan before slicing. Enjoy as-is or with a dusting of powdered sweetener or keto whipped cream.