3/4 cup unsweetened cocoa powder
1 1/2 cups all-purpose flour
1 1/2 cups sugar
1 1/2 teaspoons baking soda
3/4 teaspoon baking powder
3/4 teaspoon salt
2 large eggs
3/4 cup warm water
3/4 cup buttermilk
3 tablespoons safflower oil
1 teaspoon pure vanilla extract
Preheat oven to 350 degrees. Line standard muffin tins with paper liners; set aside. Sift together 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, about 3 minutes. Scrape down the sides and bottom of bowl to assure batter is well mixed.
Divide batter evenly among muffin cups, filling each 2/3 full. Bake until tops spring back when touched, about 20 minutes, (about 10 minutes for mini) rotating pan once if needed. Transfer to a wire rack; let cool completely.
Source: Martha Stewart, 2004
Makes 18 to 24 regular size or 66 mini size