Preheat your oven to 350°F (177°C). Grease and flour three 8-inch round cake pans.

In a large mixing bowl, combine the sugar, flour, cocoa powder, baking powder, baking soda, and salt.

Add eggs, buttermilk, oil, and vanilla. Beat on medium speed for 2 minutes. Stir in boiling water (batter will be thin).

Divide batter evenly into prepared pans. Bake for 25–30 minutes, or until a toothpick inserted into the center comes out clean.

Cool the cakes in pans for 10 minutes, then turn out onto wire racks to cool completely.

In a medium saucepan over medium heat, combine evaporated milk, sugar, egg yolks, and butter.

Cook, stirring constantly, until thickened and golden (about 10–12 minutes). Remove from heat.

Stir in vanilla, coconut, and pecans. Let cool to room temperature before spreading.

In a medium bowl, cream butter until smooth. Sift in cocoa and powdered sugar alternately with milk, beating until fluffy.

Mix in vanilla. Add more milk if needed to achieve a spreadable consistency.

Place one cake layer on a plate and spread with half of the coconut-pecan filling. Top with the second cake layer and spread with the remaining filling. Place the final layer on top.

Frost the sides and top with chocolate fudge frosting. Decorate with additional pecans or coconut, if desired.