Preheat your oven to 425°F and line your cupcake pan with 4 liners.
In a small bowl, whisk together flour, cocoa powder, baking soda, baking powder, and salt. Set aside.
In a medium bowl, whisk together sugar, sour cream OR yogurt, egg white, coffee OR milk, vegetable oil, and vanilla extract until smooth. Stir in dry ingredients until just combined. Fold in chocolate chips and divide batter between your prepared cupcake cups, filling them 80% of the way full (this should use all to almost all of your batter).
For extra pretty muffins, drop a couple chocolate chips over the tops of the batter before they go into the oven.
Bake for 8 minutes, turn the temperature down to 350°F and continue to bake for an additional 6 to 9 minutes. Muffins are done when a toothpick inserted into the center of the muffins comes out with just a few dry crumbs.
Cool in the tin for 5 minutes before transferring to a cooling rack. Serve warm and enjoy or cool completely and store in an air-tight container for up to 2 days.