Position a rack in the center of the oven and preheat to 425°F. Line muffin pans with paper or parchment liners (this makes about 16, so use two pans or bake in two rounds).
In a large bowl, whisk together the flour, baking powder, baking soda, and salt for 20 to 30 seconds so the leavening is evenly distributed.
In a separate bowl, whisk together the sugar, oil, eggs, sour cream, milk, vanilla, and discard until smooth with no streaks of sour cream or discard.
Pour the dry ingredients into the wet and fold gently with a spatula until a few streaks of flour remain.
Reserve about 25 g of chocolate chips for the tops. Fold the rest into the batter, stopping as soon as the dry flour disappears. Do not overmix. The batter should be thick but soft.
Divide the batter among the cups, filling them nearly full (about 90 to 95 g each) for taller domes. Sprinkle the reserved chips over the tops. A light sprinkle of coarse sugar is optional.
Bake at 425°F for exactly 5 minutes. Without opening the oven door, reduce the temperature to 350°F and continue baking 15 to 18 minutes, checking at 14 to 15 minutes.
They're done when the tops spring back, a toothpick hits melted chocolate but no raw batter, or the center reads about 200 to 205°F.
Let the muffins stand in the pan 5 to 7 minutes, then transfer to a wire rack. Do not cool them fully in the pan, or the bottoms overcook and the liners turn soggy.