Preheat your oven to 350°F (175°C) and line a cupcake tin with paper liners.

In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking soda, baking powder, and salt until well combined.

In another bowl, mix the egg, buttermilk, vegetable oil, and vanilla extract until smooth.

Gradually add the wet ingredients to the dry ingredients, mixing until just combined. Be careful not to overmix to keep the cupcakes light and fluffy.

Slowly stir in the boiling water until the batter is smooth. The batter will be thin, which is normal.

Pour the batter into the prepared cupcake liners, filling each about 2/3 full.

Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center comes out clean.

Remove from the oven and allow to cool in the tin for 5 minutes before transferring to a cooling rack to cool completely.

In a saucepan over medium heat, combine the sugar, evaporated milk, butter, and egg yolks.

Cook while stirring constantly until the mixture thickens and starts to bubble, about 10-12 minutes. This step is crucial for achieving the right texture.

Remove from heat and stir in the vanilla extract, shredded coconut, and chopped pecans. Allow the frosting to cool to room temperature.

Once the cupcakes are completely cooled, generously frost each cupcake with the coconut-pecan frosting.