Preheat the oven:
Preheat your oven to 325°F (163°C). Grease and flour a 9×5-inch loaf pan or a bundt pan.

Prepare the cake batter:
In a medium bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt.
In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy, about 3-4 minutes.
Add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract.
Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk, beginning and ending with the dry ingredients. Mix until just combined.
Stir in the hot water, which will help create a smoother batter and lighter texture.

Bake the cake:
Pour the batter into the prepared pan and smooth the top. Bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.
Let the cake cool in the pan for 10-15 minutes, then transfer it to a wire rack to cool completely.

Make the coconut-pecan topping:
In a medium saucepan, combine the evaporated milk, sugar, butter, egg yolks, and salt. Cook over medium heat, stirring constantly, until the mixture thickens and starts to bubble, about 5-7 minutes.
Remove from heat and stir in the vanilla extract, shredded coconut, and chopped pecans. Let the mixture cool for a few minutes before spreading it on the cooled pound cake.

Assemble the cake:
Once the cake has cooled completely, spread the coconut-pecan topping evenly over the top. Slice and serve!