Preheat oven to 350°F and make sure your oven racks are in the middle of the oven. Spray 3 8" x 2" cake pans with baking spray (or lightly butter and flour), then line the bottom of the pan with parchment paper, then spray parchment paper with baking spray. Set aside.
In a large bowl, take chopped chocolate and mix with hot espresso until the chocolate is fully dissolved. Set aside and let cool to room temperature.
In a different large bowl, sift flour, cocoa powder, salt, baking soda, and baking powder. Stir all ingredients together and set aside.
In a separate bowl, beat egg whites at a medium speed until they appear foamy. Then increase speed to high until the egg whites are firm enough that if you run the beaters through them they leave a line and egg whites will cling onto your beaters. Slowly beat in 1 tbsp of reserved white sugar until well incorporated.
In a large mixing bowl (preferably a stand mixer) beat egg yolks, white sugar, brown sugar, and vanilla extract together until well combined and fluffy. Slowly drizzle in vegetable oil on medium speed to emulsify the oil into the egg mixture. Add espresso chocolate mixture and combine well.
Switch to a paddle attachment (spatula if hand mixing) and add ⅓ dry ingredients and combine well, then add ½ buttermilk, alternating until all ingredients are mixed into the batter. Make sure to only mix until combined and no more or your cake will get tough and chewy. Fold in ⅓ egg whites at a time into cake batter until well incorporated but still fluffy. Do not mix as this will break the air of the egg whites and leave your cake dense instead of light and fluffy. Your batter should resemble chocolate mousse in terms of airiness when the egg whites are all folded in.
Separate cake batter equally between the 3 cake pans, gently tapping the pans on the counter to remove any air bubbles. Bake for 30-35 minutes, until a toothpick or cake tester inserted into the center of the cake comes out clean. Make sure to rotate your cakes about half way through baking time for even baking. Let cool on baking rack for 15 minutes, then invert onto the baking rack to finish cooling completely before frosting.
Coconut Pecan Frosting
Preheat oven to 350°F. Spread pecans onto a single layer on a baking sheet and bake for 6-8 minutes, until the pecans are light brown and fragrant. Stir occasionally to ensure even browning. Let cool.
In a medium saucepan, combine brown sugar and egg yolks until the egg yolks are combined into the sugar, this will help prevent accidental strings of egg yolk in the end result. Then add evaporated milk, butter chunks, and salt and turn the burner on to medium heat. Bring to a gently boil, stirring constantly, until the mixture thickens and turns golden brown, about 6-8 minutes. Take off the heat and stir in toasted pecans, coconut flakes, and vanilla and let cool until it has a spreadable texture, about 45-60 minutes.
Chocolate Frosting
Sift cocoa powder and powdered sugar together to make sure you have no lumps. Using your stand and hand mixer, cream butter and ⅓ of the cocoa/sugar mixture together. Once well combined slowly drizzle ½ whipping cream, mixing well. Alternate with remaining sugar mixture and whipping cream until both ingredients are completely used. Mix in vanilla extract and sugar. You may need to add more cream to get your desired texture, making sure it's firm enough to hold it's shape while still easy to push through a piping nozzle.
Assembly
Add ⅓ of the chocolate frosting to a piping bag (if you want a decorative piped edge on top of your cake use that nozzle now do you don't have to worry about switching it out). Put a small dollop of chocolate frosting in the center of your cake stand and gently place the first layer of cake. Pipe icing around the top edge of the cake in a smooth line, this will allow you to add the coconut pecan frosting without having it spill over when you add the additional layers. Add ⅓ of the coconut frosting to the first layer, smoothing it out to the chocolate frosting. Repeat with the second and third layer.
Now use the chocolate icing that's not in the piping bag to ice the sides of the cake. I like to use a long icing spatula for this to make it quick. Once smoothed out over the whole cake, then use the rest of the icing in the piping bag to pipe a decorative edge on the top border of the cake. Finish by pressing toasted coconut around the bottom sides of the cake. Now, dig in and enjoy your amazing creation!
Notes
Separating Eggs: separating eggs is much easier when the eggs are cold so I would highly recommend separating them when you remove them from the refrigerator then let them come up to room temperature for the recipe.Toasted Coconut for Decorating: If you've decided to add toasted coconut for decorating your cake simply add to a baking sheet in a single layer and bake at 350°F for 8-10 minutes. Stir every few minutes to allow for even toasting. This is a great step to do right after you toast the pecans since you can reuse the baking sheet (YAY! Less dishes!) and the oven is already at the right temperature. Just make sure coconut is completely cooled before using or it will melt your icing and make a mess.