Make the Cupcakes:
Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners.
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and cocoa powder. Set aside.
In a large mixing bowl, beat the butter, granulated sugar, and brown sugar until light and fluffy, about 3 minutes.
Add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract.
Gradually add the dry ingredients to the wet ingredients, alternating with the milk. Mix until just combined.
Pour in the boiling water and mix until the batter is smooth and well combined (it will be thin).
Gently fold in 6 crushed Oreos.
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 the cupcakes cool in the tin for 5 minutes before transferring them to a wire rack to cool completely.
Make the Frosting:
In a large mixing bowl, beat the softened butter until creamy.
Gradually add the powdered sugar, one cup at a time, mixing well after each addition.
Stir in the vanilla extract and heavy cream (or milk) until the frosting reaches your desired consistency.
Fold in 6 crushed Oreos.
Assemble the Cupcakes:
Once the cupcakes have cooled, pipe or spread a generous amount of cookies and cream frosting on top of each cupcake.
Garnish with additional Oreo halves or crushed cookies on top of the frosting.