Preheat the oven to 425°F and prepare a muffin pan by lining it with paper liners or lightly greasing each well.
Whisk the eggs, sour cream, milk, vanilla, and vegetable oil together in a large bowl until smooth.
Whisk the flour, cocoa powder, sugar, baking powder, baking soda, and salt together in a separate bowl.
Add the dry ingredients to the wet ingredients and whisk until just combined without overmixing.
Fold in the chocolate chips with a spatula until evenly distributed.
Fold in 1 cup of the crushed Oreos as the final mix-in.
Divide the batter evenly among 12 muffin wells, filling each about ¾ full.
Sprinkle the remaining 1 cup of crushed Oreos over the tops.
Bake at 425°F for 5 minutes, then reduce the heat to 350°F (without opening the oven) and continue baking for 13–15 minutes or until a toothpick comes out with a few moist crumbs.
Cool in the pan for 5 minutes before transferring to a wire rack to cool completely.