Preheat oven to 350 degrees.
Separate oreo filling from cookies. Set filling aside and crush 2 cookie halves. Set aside.
Combine flour, sugar, cocoa powder, baking soda, and salt in a bowl.
Combine milk, vegetable oil, and vanilla in a separate bowl. Add to dry ingredients and stir until combined.
Line muffin with two liners and place whole cookie halves in the bottom. Add batter into the tins on top of the cookies. Bake for 25 minutes or until you can stick a toothpick in it and it comes out
Set aside muffins to cool. As they are cooling, combine cream cheese and butter in a bowl until smooth. Add powdered sugar and combine. Add mint filling and stir until incorporated.
Frost cupcakes with cream cheese frosting and sprinkle with crushed cookie bits.