Preheat oven to 350°F. Grease three 8-inch round cake pans; set aside.
In a small bowl, pour boiling water over chocolate chips and stir until all chocolate is melted and the mixture is smooth. Set aside to cool.
In a large bowl using a hand mixer (or stand mixer), cream butter and sugar until light and fluffy.
Add egg yolks, one at a time, beating after each yolk is added. Add vanilla and melted chocolate mixture and mix until well combined.
Sift together flour, baking soda and salt. Add sifted dry ingredients, alternating with buttermilk, beating after each addition until batter is smooth. Fold in stiffly beaten eggs whites.
Divide batter into cake pans and bake for 30 to 35 minutes, until a toothpick inserted in the center comes out clean. Cool completely.
Coconut Pecan Frosting: Combine evaporated milk, sugar, egg yolks and butter in a sauce pan.
Cook over medium-high heat, stirring constantly, until mixture thickens, about 12 minutes.
Remove from heat, add vanilla. Add shredded coconut and chopped pecans. Beat until cool and the mixture reaches spreading consistency. (Frosting makes enough to cover tops of three 8-inch layers. Double recipe to cover entire cake.)
Frost cake as desired with Coconut Pecan Frosting. Serve immediately or store in an airtight container until ready to serve.