Preheat oven to 350°F. Grease or line a mini muffin pan.
In a bowl, whisk flour, sugars, baking powder, baking soda, and salt.
In another bowl, mix oil, milk, egg, vanilla, and sour cream.
Combine wet and dry ingredients until just mixed—don’t overmix.
Fold in mini chocolate chips.
Scoop into mini muffin pan, filling about ¾ full.
Bake 10–12 minutes, until just set (do NOT overbake).
Let cool in pan a few minutes, then remove.