Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners.
In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
In another bowl, combine the buttermilk, vegetable oil, egg, and vanilla extract.
Pour the wet ingredients into the dry ingredients and mix until just combined.
Gradually add the boiling water, mixing until the batter is smooth.
Pour the batter into the prepared cupcake liners, filling them about two-thirds full.
Bake in the preheated oven for 18-20 minutes, or until a toothpick comes out clean.
Let the cupcakes cool in the pan for 5 minutes before transferring to a wire rack.
Once completely cool, frost with your favorite chocolate frosting.
Decorate with sprinkles or chocolate shavings if desired.