Preheat the oven to 350°F (175°C) and line a muffin tin with cupcake liners.
Whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt in a large mixing bowl.
Beat the softened butter until creamy in another bowl. Add the eggs and vanilla extract, mixing until well combined.
Gradually add the dry ingredients to the wet mixture, alternating with the milk. Mix until just combined, then fold in the crushed chocolate sandwich cookies.
Divide the batter evenly among the cupcake liners, filling each about 2/3 full.
Bake for 18-20 minutes or until a toothpick inserted into the center comes out clean. Let them cool completely before moving to frosting.
Beat the softened butter until creamy in a mixing bowl.
Gradually add the powdered sugar, alternating with heavy cream and vanilla extract while beating until fluffy.
Frost each cooled cupcake generously with the buttercream frosting and sprinkle crushed chocolate sandwich cookies on top for that extra crunch and flavor!