Preheat the oven to 425°F / 220°C. Line a 12-cup muffin pan with paper liners.
Whisk 2 cups of all-purpose flour, 1 cup of sugar, ½ cup of natural unsweetened cocoa powder, 1 teaspoon of baking soda, and ½ teaspoon of salt. Stir in 1¾ cups of semisweet chocolate chips.
Whisk 2 eggs, ¾ cup of full-fat sour cream, ½ cup of vegetable oil, ½ cup of whole milk, and 1½ teaspoons of vanilla extract. Fold into the dry ingredients just until combined.
Fill the liners to the top. Bake for 5 minutes, then lower the oven to 350°F / 175°C and bake for 15-16 minutes more, until a toothpick inserted into the center comes out clean.
