Preheat oven to 350 degrees F and line the bottom of three 4-inch cake pans (3 layers) or two 6-inch 2 cake pans (2 layers) with parchment paper cut into circles. Grease the sides with coconut oil. In a large mixing bowl, combine cassava flour, coconut flour, baking soda, and sea salt.
1/2 cup cassava flour, 1/2 cup coconut flour, 1 tsp baking soda, 1/8 tsp sea salt
In a separate bowl, whisk together blended banana, coconut milk, coconut oil, and apple cider vinegar (and coconut sugar, if using).
1 cup blended ripe bananas, 1 cup coconut milk, 1/4 cup coconut oil, 1 tbsp apple cider vinegar, OPTIONAL: 1/4 cup coconut sugar
Add wet ingredients to dry and stir until just combined.
Divide the batter into the prepared cake pans evenly. Tap the pans on the countertop a few times to evenly distribute the batter, then flatten out the top with the back of a spoon. It'll be a bit thicker than a standard cake batter.
Bake for 20-25 minutes until a toothpick inserted into the center of the cake comes out clean.
Cool on the countertop for 20 minutes, then remove from the cake pans carefully. Cool completely at room temperature or in the refrigerator.
MAKE THE FROSTING: If using coconut sugar and/or dehydrated fruit for coloring, place them in the food processor and blend until powdery.For Coconut Frosting - Carefully remove the can of coconut cream or milk from the fridge, slowly turn the can upside down, and open it with a can opener. Pour out the coconut water you see on the top, and scoop out the solid cream on the bottom. Combine the cream with powdered sugar and dehydrated fruit (if using), and use a stand mixer or a handheld mixer to beat until stiff peaks form.For Heavy Whipping Cream Frosting - Combine the chilled heavy whipping cream with powdered sugar and dehydrated fruit (if using). Use a stand mixer or a handheld mixer to beat until stiff peaks form. 1 14 oz can of full-fat coconut milk or cream, OR 1 cup heavy whipping cream, chilled, Optional sweetener: 3-4 tbsp powdered sugar, Optional coloring: 3/4 cup freeze-dried fruit of choice*
Frost the cake. If the cake layers are not flat on the top, use a serrated knife to to cut a thin layer of the tops of the cakes. Place 1 cake on a cake stand or plate, then frost the top with some of the frosting. Add another layer, then repeat (skip for a 2-layer cake). Add the final layer, then spread the frosting all over the top and sides. Garnish and decorate to your liking.
Refrigerate until ready to serve.