1. Prepare the Crust:

1. Preheat the oven to 350°F (175°C) and grease two 9-inch round cake pans.
2. In a large bowl, combine the granulated sugar, brown sugar, flour, cocoa powder, baking soda, baking powder, and salt.
3. Add eggs, melted butter, buttermilk, and vanilla extract to the dry ingredients and beat until well combined.
4. Gradually add the boiling water to the batter, mixing slowly until smooth.
5. Divide the batter evenly between the prepared cake pans and bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
6. Allow cakes to cool in the pans for 10 minutes, then remove from pans and cool completely on a wire rack.
7. For the frosting, in a medium saucepan over medium heat, stir together evaporated milk, sugar, egg yolks, and butter until thickened.
8. Remove from heat and stir in vanilla, coconut, and pecans. Let cool until spreading consistency.
9. Spread frosting between layers and over the top and sides of the cake.