One-Bowl Chocolate Cupcakes

Preheat oven to 350 degrees. Line standard muffin tins with paper liners. Sift cocoa powder, flour, sugar, baking soda, baking powder, and salt into a large bowl. Add eggs, warm water, buttermilk, oil, and vanilla, and mix until smooth.

Divide batter among muffin cups, filling each 2/3 full. Bake until tops spring back when touched, about 20 minutes. Transfer cupcakes to wire racks, and let cool. Cupcakes will keep, covered, for up to 3 days.