Preheat oven to 400. Line or grease muffins tins.
Combine flour, white sugar, brown sugar, cocoa, baking soda and salt.
Add sour cream, egg, milk and vanilla.
Fold in chocolate chips.
Fill prepared muffin tins to the top.
Bake in preheated oven for 15 minutes or until a toothpick comes out clean.
If sprinkling with coarse sugar take the muffins out a couple minutes early and sprinkle with coarse sugar and return to oven to finish baking.