Preheat the oven to 300 degrees Fahrenheit. Line a 12-cup muffin pan with cupcake liners. Line a second pan with 2-4 liners – this recipe makes about 14 to 16 cupcakes. Set aside.
In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking soda and salt. Set aside.
In a medium bowl, combine the egg, milk, oil, and vanilla.
Add the wet ingredients to the dry ingredients and mix with a spatula or wooden spoon until well combined.
Pour the water into the batter and mix until well combined. The batter will be thin.
Pour or spoon the batter into the cupcake liners. Fill only halfway to prevent spilling or sinking. Bake for 18 to 23 minutes or until a toothpick inserted in the middle of a cupcake comes out clean or just with a few crumbs.
Remove the cupcakes from the oven and allow to cool completely before frosting.