Preheat oven to 350 degrees F and prepare three 8 inch cake pans. (We grease and flour our pans, and then line the bottom of the pans with circles of parchment.)
Mix butter at medium speed until softened and smooth.
Gradually add sugar, mix on medium speed 4 to 5 minutes until lightened in color and fluffy.
Add egg yolks, one at a time, mixing after each addition until the yellow of the yolk is blended. Add Vanilla extract.
In a separate bowl, add flour, cocoa, baking soda and salt. Whisk at least 30 seconds to blend.
With the mixer on low speed, add the flour mixture to the butter mixture alternately with buttermilk, beginning and ending with the flour mixture (that is 3 additions of dry ingredients and 2 additions of buttermilk). Mix just until blended after the last addition.
.Stir in pecans and coconut with a spoon.
Beat egg whites at high speed until stiff peaks form. Using a spatula or spoon, gently fold into batter. Scoop batter into three 8 cake pans.
Bake at 350 degrees for 20 to 25 minutes or until inserted toothpick comes out clean. Cool in pans for 10 minutes, then remove and cool on wire racks.
***No Buttermilk? Here is a substitution: Measure out 1 ½ cups milk, add 1 Tablespoon plus 2 teaspoons vinegar, let sit for 5 to 10 minutes, it will begin to look slightly curdled.