Preheat your oven to 350 degrees and line the bottom of two 9-inch cake pans with parchment paper, generously rubbing coconut oil up the sides of them. Set aside.
Place the mashed avocado into a small food processor, mine is 3 cups, and blend it until it's really creamy and smooth, scraping down the sides as necessary.*** Transfer into a large bowl.
Add the honey, vanilla and egg yolks into the bowl, making sure to place the egg whites into a large, separate bowl. Beat the mixture until creamy and well mixed.
Place the dark chocolate into a small, microwave-safe bowl and microwave on 50% power in 30 second intervals, stirring between each interval, until the chocolate is smooth and melted. Add the chocolate into the avocado mixture and beat until well incorporated.
In a seperate small bowl, stir together the coconut flour, tapioca flour, baking soda and salt.Stir it into the avocado mixture until mostly mixed in. Then, beat it with the hand mixer until totally mixed.
Wash and dry your beaters REALLY well and then beat the egg whites on high speed until they form stiff peaks, which takes about 4 minutes.
Gently place the whipped egg whites into the bowl with the cake batter and GENTLY fold them into the batter until no white streaks remain.
Divide the batter between the two prepared pans and bake until a toothpick inserted in the center comes out clean, about 25 minutes. Let cool to room temperature in the pans, and then transfer to a wire rack to cool completely.