Preheat oven to 350°F (175°C). Line a muffin tin with cupcake liners.
In a large bowl, whisk together the flour, cocoa powder, sugar, baking powder, baking soda, and salt.
Add the eggs, vegetable oil, and vanilla extract. Mix until combined.
Gradually add the milk and hot water, mixing until smooth.
Pour the batter into the cupcake liners, filling each about ⅔ full.
Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
Let cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.