Prep oven and pans. Position a rack in the center of your oven. Pre-heat oven to 350°F. Prepare two muffin pans with cupcake liners. You can also lightly spray the pan and liners with non-stick cooking spray so they won't stick.
Combine dry ingredients. In a large mixing bowl, sift together the sugar, flour, cocoa, baking powder, and baking soda. Stir in the salt. Set aside.1 cup (200 g) granulated sugar 1 cup (120 g) all-purpose flour ½ cup (42 g) unsweetened Cocoa powder ¾ teaspoons baking powder ¾ teaspoons baking soda ½ teaspoon salt
Combine wet ingredients. In a second large mixing bowl, whisk together the eggs, milk, sour cream, oil, vanilla extract until well combined. 1 large egg ¼ cup (60 ml) milk ¼ cup (57 g) sour cream ¼ cup (60 ml) vegetable oil 1 teaspoon vanilla extract
Combine wet and dry ingredients. Add the wet ingredients to the flour mixture, and stir with a rubber spatula, together just until the last of flour has been incorporated.
Add hot coffee. Stir in the coffee to batter and stir to combine. (batter will be thin). ½ cup (120 ml) hot coffee
Bake cupcakes. Fill each cupcake well about 3/4 cup full of batter. I like to let the cupcakes rest for 10 minutes before baking so they bake up a bit taller. Bake for 18-22 minutes or until wooden pick inserted in center comes out clean, rotating pans halfway through baking. Remove cupcakes from the oven and cool in the pans for 5 minutes, then transfer to a cooling rack and cool on a wire rack. Cool completely.