Preheat the oven to 375°F. Line a 12-cup muffin pan with cupcake liners or spray with non-stick cooking spray.
Sift together flour, cocoa powder, salt, baking powder, baking soda, and sugar in a small bowl and set aside.
In a large mixing bowl, beat or whisk together eggs, melted butter, vanilla extract, buttermilk, and sour cream.
Dump dry ingredients into the butter/eggs/sour cream mixture and stir gently, just until combined. Do not overmix.
Add chocolate chips and stir just until they are distributed throughout the batter.
Divide batter between the 12 muffin cups in the prepared pan, filling each cup about ¾ of the way full.
Bake for approximately 20 minutes or until a toothpick inserted in the center of the muffins comes out clean.
Cool muffins in pan for 5 minutes. Remove muffins to a cooling rack to finish cooling.