1. Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.

2. In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and cocoa powder. Set aside.

3. In a large bowl, cream the butter, granulated sugar, and brown sugar until light and fluffy, about 3-4 minutes.

4. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.

5. Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk, beginning and ending with the dry ingredients. Mix until just combined.

6. Stir in the hot water until the batter is smooth and thin.

7. Divide the batter evenly between the prepared cake pans. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.

8. Allow the cakes to cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.

For the Frosting:

1. In a medium saucepan, combine the evaporated milk, sugar, and butter. Cook over medium heat, stirring constantly, until the mixture begins to simmer.

2. Gradually stir in the beaten egg yolks and cook for 2-3 minutes, until the mixture thickens slightly.

3. Remove from heat and stir in the vanilla extract, coconut, and pecans. Allow the frosting to cool and thicken before using.

4. Once the cakes have cooled, spread a generous layer of frosting on top of one of the cakes. Place the second cake on top and frost the top and sides of the entire cake.

5. Slice and serve.