Preheat oven to 350 degrees F. Line bottoms of three 8-inch round pans with parchment paper; set aside.
To make the cake:
Melt chocolate over very low heat; cool. In a small mixing bowl, sift flour with sugar, Clabber Girl Baking Soda, Clabber Girl Baking Powder and salt; set aside.
Stir butter in mixing bowl to soften. Add flour mixture, 3/4 cup of buttermilk and vanilla. Mix to dampen flour, beat for 2 minutes at medium speed, scraping bowl occasionally. Add melted chocolate, eggs and remaining buttermilk. Beat for 1 minute longer.
Pour into prepared layer pans. Bake at 350 degrees F for 35 minutes, or until toothpick inserted in center comes out clean.
To make the frosting:
In a medium saucepan combine evaporated milk, sugar, egg yolks, margarine or butter and vanilla. Cook and stir over medium heat until mixture thickens, about 12 minutes. Remove from heat; add chopped pecans and coconut. Cool until frosting is of spreading consistency, beating occasionally.
Cool cake in pans for 15 minutes; remove from pans and cool on wire racks. When the cake is completely cooled, spread frosting on layers and stack.
Recipe by Nancy and Gary Hull.