Called "emergency" cupcakes because they're for emergencies, as in "Mom, I forgot to tell you that you're supposed to bring cupcakes to school today...
Preheat oven to 375°F. Line 12 regular-sized muffin tin with paper or foil liners.
Combine flour, cocoa, sugar, baking soda, and salt in a blender. Cover with the lid and blend on medium-speed until blended. Pour in the water, oil, egg and vanilla. Cover with the lid and blend on medium-high speed until smooth and well blended, stopping to scrape down the sides once or twice.
Pour into prepared muffin tin, dividing evenly. Bake until toothpick inserted in center of one cupcake comes out clean, about 15 to 17 minutes.
Transfer to rack to cool for about 10 minutes, and then carefully remove cupcakes from the pan and set them on the rack to cool completely before frosting.