Preheat oven to 350°F. Line 2 9-inch round cake pans with parchment paper and spray with nonstick spray. Set aside.
In a medium-sized bowl, whisk together the flour, baking soda, baking powder and salt.
2 cups all-purpose flour, 1¾ teaspoons baking soda, 1½ teaspoons baking powder, 1 teaspoon kosher salt
In a large mixing bowl, whisk together the sugar, brown sugar, milk, sour cream, vegetable oil, eggs, egg yolks, and vanilla. Whisk in the cocoa powder until combined.
⅔ cup granulated sugar, ⅔ cup brown sugar, ⅔ cup milk, ½ cup sour cream, ⅓ cup vegetable oil, 2 large eggs, 2 egg yolks, 2 teaspoons pure vanilla extract, ⅔ cup unsweetened cocoa powder
Add in the flour mixture and whisk until incorporated. Add in the hot water and hot coffee and whisk until smooth. The batter will be runny at this point.
½ cup hot water, ½ cup hot coffee
Divide the batter evenly (about 644 grams per pan) into the cake pans and place into the preheated oven to bake for 25 minutes, or until a toothpick inserted comes out clean or with moist crumbs. Once baked, remove from the oven and place onto a cooling rack to cool completely.
While the cakes are cooling, make the icing: Combine all of the icing ingredients except for the shredded coconut and pecans in a large saucepan. Place over medium heat and let simmer for 6-7 minutes, whisking constantly. Fold in the shredded coconut and chopped pecans. Set aside.
4 egg yolks, ½ cup brown sugar, ½ cup granulated sugar, 8 ounces evaporated milk, ¼ cup unsalted butter, ¼ cup vegetable shortening, 1 teaspoon pure vanilla extract, 1⅔ cups sweetened shredded coconut, 1 cup chopped pecans
To make the buttercream, combine all of the buttercream ingredients (except the milk and chocolate syrup) in the bowl of a stand mixer fitted with the paddle attachment. Beat on high-speed for 5-6 minutes, or until a smooth, fluffy frosting has formed. If you find that your frosting is dry or too thick, add in milk a tablespoon at a time until you reach your desired consistency. Fill a piping bag fitted with a star tip with ½ cup of frosting.
5 cups powdered sugar, 1½ cups unsalted butter, 1 teaspoon pure vanilla extract, ½ teaspoon kosher salt, Milk, ⅔ cup unsweetened cocoa powder
To assemble the cake, place one of the cool cake layers onto a plate or cake stand.
Chocolate Drizzle
Using an offset spatula or rubber spatula, spread about ¼ cup of buttercream over the cake layer. Pipe a buttercream ring around the edges of the cake to form a barrier for the icing. Spoon half of the coconut-pecan icing into the middle of the buttercream ring.
Place the second layer of cake on top ensuring that the edges meet and that cake does not hang over on one side. Finish spreading the buttercream over the entire surface and sides of the cake. Drizzle chocolate syrup over the edges of the cake to make it look like it has dripped, if desired. Pipe a ring of buttercream swirls around the edge of the cake. Spread the remaining coconut-pecan icing into the middle of the swirls and smooth. Drizzle additional chocolate syrup in a crosshatch pattern over the frosting. Slice and serve.