For the Cake:
Preheat the oven to 350°F (175°C). Grease and line cake pans with parchment paper.
In a large bowl, whisk together sugar, flour, cocoa powder, baking powder, baking soda, and salt.
Add eggs, milk, oil, and vanilla extract. Beat until smooth.
Slowly mix in boiling water until the batter is thin but well combined.
Divide the batter evenly between the prepared pans.
Bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean.
Cool the cakes in the pans for 10 minutes, then transfer them to a wire rack to cool completely.
In a saucepan, combine evaporated milk, sugar, egg yolks, and butter. Cook over medium heat, stirring constantly, until thickened (about 10–12 minutes).
Remove from heat and stir in vanilla, coconut, and pecans. Let cool completely.
Place one cake layer on a serving plate. Spread a thick layer of frosting on top.
Add the second layer and repeat. Finish with frosting on top (no need for the sides).
Garnish with extra coconut or pecans if desired.