Preheat the oven to 350F. Spray cake pans with non-stick spray and line with parchment paper.
In a medium bowl place the chocolate and water. Microwave on high for 1 minute. Whisk well and reheat another 15-30 seconds if needed until the mixture is smooth. Set aside.
In an extra large bowl or the bowl of a stand mixer, combine the sugar and butter with whisk attachments until light and fluffy. Add in the egg yolks one at a time until combined.
Add the melted, and now cooled, chocolate as well as the vanilla extract. Mix until combined.
In a separate large bowl combine the flour, baking soda, and salt.
Working in two batches, alternate adding the flour and buttermilk to the chocolate mixture. Mix until well combined.
In another separate bowl, use a hand held mixer to beat the egg whites until stiff peaks form.
Fold the egg whites into the cake the batter with a rubber spatula.
Divide evenly amongst the three cake pans and bake for 30 minutes.
Run a small metal spatula or butter knife along the edge of the cake pans to loosen the cake. Allow to cool in pans for 15 minutes. Remove cakes from pans and allow to cool on wire racks.
Assemble the cake by placing layers of coconut-pecan filling between the layers of cake with the final layer on top in the center of the cake, spread almost all the way to the edge.
Use the chocolate frosting to cover the outside of the cake. Use a large star or large closed-star tip on a piping bag to create decorative boarder on the top of the cake.
Chill in the refrigerator for easier cutting.
Notes
Don’t have buttermilk? Add 1 Tablespoon of vinegar or lemon juice to a cup of milk and allow to rest for 10 minutes.
Use a larger star or a closed-star tip on a piping bag or gallon sized Ziploc bag to pipe top chocolate boarder.