Preheat the oven to 350°F (175°C)
Grease and line three 9-inch round cake pans
In a bowl, whisk together flour, cocoa powder, baking soda, and salt
In another bowl, cream butter and sugar until light and fluffy
Beat in egg yolks one at a time
Add vanilla extract
Add buttermilk and dry ingredients alternately, mixing until combined
In a separate bowl, beat egg whites until stiff peaks form
Fold the egg whites gently into the batter
Divide the batter evenly among the prepared pans
Bake for 25 to 30 minutes
Cool the cakes in the pans for 10 minutes
Remove from pans and cool completely on wire racks
Make the coconut-pecan frosting by cooking evaporated milk, sugar, egg yolks, butter, and salt over medium heat
Stir constantly until thickened
Remove from heat and stir in vanilla, shredded coconut, and chopped pecans
Let the frosting cool to spreading consistency
Place one cake layer on a serving plate
Spread frosting over the top
Repeat with the remaining layers
Frost the top of the cake
Serve as desired