Preheat the oven to 350°F (175°C) and line a muffin tin with paper liners.
In a medium bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt.
In a large bowl, mix the granulated sugar, brown sugar, sour cream, vegetable oil, eggs, and vanilla extract until well combined.
Gradually add the dry ingredients to the wet ingredients, stirring until just combined.
Fold in the chocolate chips.
Spoon the batter into the prepared muffin tin, filling each cup about 2/3 full.
Bake for 18-20 minutes or until a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.