Preheat the oven to 325⁰F; oil a 9x13-inch baking dish; set aside.
In a medium-sized bowl, whisk together the almond flour, coconut flour, cocoa powder, cinnamon, baking powder, baking soda, and salt; set aside.
In the bowl of your mixer, beat together the zucchini, erythritol, coconut oil, egg yolks, and only 1/2 teaspoon liquid stevia until some of the sugar breaks down, about 3 minutes
Beat in the vanilla until just combined; set aside.
In a clean bowl, fitted with the balloon/whisk attachment (preferably the bowl and beaters should be chilled), beat the egg whites and the remaining 1/4 teaspoon liquid stevia until they become stiff, but not dry. Fold into the chocolate batter, one-third at a time, rotating the bowl as fold.
Transfer the batter to the prepared dish. Top with nuts, if desired. Bake for 55 minutes or until the middle is set and no longer jiggles when shaken.
Completely cool on a wire rack in the dish.
Slice and serve as desired. You can serve plain, top with dairy free frosting, ice cream, or whipped cream sweetened with sugar-free powdered sweetener. You can even add a little cocoa powder to the whipped cream.
Using coconut oil adds additional coconut flavor.
https://glutenfreerecipebox.com/best-low-carb-chocolate-cake/