Preheat your oven to 350°F (175°C) and line a muffin pan with cupcake liners.
In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
Add in the milk, vegetable oil, egg, and vanilla extract to the dry ingredients and mix until well combined.
Carefully pour in the boiling water, and gently mix the batter until smooth and well combined. It will be quite thin – that's the secret to the moist texture!
Divide the batter evenly among the cupcake liners, filling each about ⅔ full.
Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cupcakes to cool in the pan for about 5 minutes, then transfer to a wire rack to cool completely.
Once cooled, frost the cupcakes with your favorite chocolate frosting and sprinkle with a bit of chocolate shavings for that extra special touch.