Preheat to 350 degrees F. Grease and flour three 9-inch cake pans. Cream the butter and sugar on medium speed until light and fluffy, about 4-5 minutes. Add the eggs whites, vanilla and smashed banana. Beat on medium speed until combined, scraping down bowl as needed.
Combine the flour, baking soda, salt and baking powder in a medium bowl. Add 1/3 of the flour mixture and beat on low, until combined. Add half the buttermilk, beat until combined. Continue alternating ingredients, ending with the flour. Scrape the sides and bottom of bowl as needed. Finally add the shredded coconut and mix to combine.
Divide the batter into prepared pans. Bake for 25-35 minutes until a toothpick inserted in the middle comes out clean. Allow the cakes to cool in the pans on a cooling rack for 10 minutes. Invert the cakes onto the cooling racks and cool completely. Wrap each cake separately and freeze.
For the Whipped Chocolate Frosting:
Place all the ingredients in a clean mixing bowl and beat on high until stiff peaks form.
Unwrap the frozen cakes. Divide 1/4 of the whipped frosting on the bottom layer, 1/4 on the middle layer, and 1/2 of the frosting on the top layer. Spread the frosting evenly over the bottom layers, then stack the three cakes, level, and spread the large amount of frosting (on the top layer) over the top and down the sides. Press the shredded coconut around the bottom half and the cake and place in the fridge to chill.
For the Chocolate Ganache:
Heat the heavy cream in the microwave until it simmers. Remove and add the chocolate. Allow it to sit for 10 minutes then add the corn syrup and gently stir. Once smooth, tap the bowl on the counter to remove bubbles. Cool to room-temperature. Once the ganache is cool, pour over the top of the cake and spread to the sides, allowing the ganache to run down.
Chill until ready to serve. *When serving, I like to cut the slices then allow them to sit for a few minutes so the cake warms up a little.