Melt Chocolate: Pour boiling water over chocolate and stir until smooth.
Mix Dry Ingredients: Whisk flour, baking soda, and salt.
Cream Butter & Sugar: Beat butter and sugar until fluffy; add eggs one at a time.
Combine Batter: Mix in chocolate and vanilla, then alternate flour mixture and buttermilk.
Bake: Divide batter in pans; bake at 350°F for 30 minutes; cool completely.
Cook Frosting Base: Heat evaporated milk, sugar, butter, yolks, and salt for 12 minutes.
Finish Frosting: Stir in coconut, pecans, and vanilla; cool fully.
Assemble: Layer cake with frosting between and on top; leave sides bare.
