Preheat oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.

In a large bowl, whisk together flour, sugar, cocoa powder, baking soda, and salt.

In a separate bowl, whisk together eggs, buttermilk, oil, and vanilla extract.

Add the wet ingredients to the dry ingredients and mix until just combined.

Carefully stir in the boiling water. The batter will be thin.

Pour the batter evenly into the prepared cake pans.

Bake for 30-35 minutes, or until a wooden skewer inserted into the center comes out clean.

Let the cakes cool in the pans for 10 minutes before inverting them onto a wire rack to cool completely.

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

Cook over medium heat, stirring constantly, until thickened and bubbly. This will take about 8-10 minutes. Do not boil.

Remove from heat and stir in vanilla extract, coconut, and pecans.

Let the frosting cool and thicken slightly before spreading.

Place one cake layer on a serving plate. Spread about half of the frosting over the top.

Top with the second cake layer and spread the remaining frosting over the top and sides of the cake.

Chill the cake for at least 30 minutes before slicing and serving.