Preheat the oven to 375°F. Line an 8-inch square baking pan with parchment paper and set aside.

In a large bowl, whisk together cocoa, both flours, salt, baking powder and baking soda.

Whisk thoroughly to eliminate any lumps. Set aside.

Add bananas, dates, coconut milk, 2 tablespoons water and vanilla to a blender.

Blend until dates are chopped very small and the mixture is thick and smooth, 1 full minute or more.

Make a well in the center of the flour mixture.

Pour in the banana mixture, and fold the wet ingredients into the dry ingredients until just combined, taking care not to overwork the batter.

Pour the batter into the prepared pan and smooth the top evenly with a spatula.

Sprinkle coconut on top.

Bake until the top is firm and a toothpick inserted in the cake comes out clean, about 45 minutes.

Let the cake cool in the baking pan on a cooling rack for 5 minutes, then remove cake from the pan and cool completely.

Peel the parchment paper off the cake and cut cake into squares for serving.

Wrap any remaining cake tightly and store at room temperature or in the refrigerator.