Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners.
In a large mixing bowl, combine the flour, sugar, cocoa powder, baking powder, baking soda, and salt. Whisk together until well blended.
Add the eggs, milk, vegetable oil, and vanilla extract to the dry ingredients. Beat on medium speed for about 2 minutes until smooth.
Carefully stir in the boiling water until the batter is well combined. 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 let the cupcakes cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.