• Preheat the oven to 375 degrees. Line 18 muffin cups with paper muffin liners and spray with cooking spray.
• Combine flour, sugar, salt, crushed cookies, cocoa powder, baking soda, and salt in a large bowl.
• Stir the sour cream, milk, oil, egg, and vanilla into the chocolate mixture until batter is just blended.
• Fill prepared muffin cups ¾ full.
• Bake in the preheated oven until a toothpick inserted in the center comes out with just a few moist crumbs, about 16-18 minutes.
• Cool in the pans for 10 minutes before removing to cool completely on a wire rack.

Topping

• Combine the powdered sugar and one tablespoon of milk. Add more milk, if needed, to make a thick glaze.
• Drizzle the glaze over the cooled muffins. Top with cookie crumbs.