Preheat your oven to 170°C (340°F) and line a muffin tin with paper liners.
Sift together the flour, baking soda, and salt in a bowl until well aerated and lumps are removed.
In a large bowl, whisk the buttermilk, vegetable oil, eggs, and vanilla extract until the mixture looks smooth and slightly frothy.
In a small bowl, combine the cocoa powder with hot water to make a thick, glossy paste; stir until smooth.
Gradually pour the cocoa paste into the wet ingredients, folding gently until fully incorporated and the mixture is dark and shiny.
Next, fold the sifted dry ingredients into the wet mixture just until combined; avoid overmixing to keep the cupcakes tender.
Divide the batter evenly among the cupcake liners, filling each about two-thirds full to allow room for rising.
Bake the cupcakes for 20-25 minutes, until a toothpick inserted into the center comes out clean and the tops are glossy and slightly cracked.
Remove the cupcakes from the oven and let them cool in the tin for about 10 minutes before transferring to a wire rack.
Allow the cupcakes to cool completely, which helps prevent frosting from melting and enhances their deep, dark appearance.
Once cooled, frost with your favorite dark chocolate or cream cheese frosting, and enjoy the striking, moist cupcakes that look like little night skies.