Cake:

1. Preheat the oven to 350°F (175°C). Grease and flour two 9-inch round baking pans.
2. In a large bowl, whisk together sugar, flour, cocoa powder, baking powder, baking soda, and salt.
3. In another bowl, beat the eggs, milk, oil, and vanilla extract until well combined.
4. Gradually add the dry ingredients to the wet mixture, mixing on medium speed until fully incorporated. Stir in boiling water (batter will be thin).
5. Divide the batter evenly between the prepared pans. Bake for 30-35 minutes or until a toothpick inserted into the center comes out clean.
6. Let the cakes cool in the pans for 10 minutes, then transfer to wire racks to cool completely.

Frosting:

1. In a medium saucepan, combine evaporated milk, sugar, egg yolks, and butter. Cook over medium heat, stirring constantly until thickened, about 12 minutes.
2. Remove from heat and stir in vanilla, shredded coconut, and chopped pecans. Let cool to room temperature.

Assembling the Cake:

1. If necessary, level the tops of the cakes. Place one cake layer on a serving plate, spread a portion of the frosting over it, and top with the second layer.
2. Spread the remaining frosting over the top and sides of the cake. Decorate with extra coconut and pecans if desired.