Preheat oven to 350°F. Line a muffin pan with cupcake liners and place one whole Oreo at the bottom of each.
In a medium bowl, whisk together flour, cocoa powder, baking soda, and salt.
In a large bowl, beat butter and sugar until fluffy. Add eggs one at a time, mixing well. Stir in vanilla.
Alternate adding dry mixture and buttermilk into the wet ingredients until just combined.
Fold in the crushed Oreos gently.
Divide the batter evenly among cupcake liners. Bake for 18-20 minutes, or until a toothpick comes out clean.
Cool completely before frosting with cookies and cream frosting. Sprinkle extra Oreo crumbs on top.