01 - Preheat the oven to 350°F (175°C). Line a standard 12-cup muffin tin with paper cupcake liners.
02 - Set one whole Oreo cookie at the bottom of each cupcake liner.
03 - In a medium bowl, whisk together the all-purpose flour, unsweetened cocoa powder, baking soda, and salt until evenly distributed.
04 - In a large bowl, beat the softened butter and granulated sugar together using an electric mixer until the mixture is pale, light, and fluffy.
05 - Add the eggs one at a time, mixing thoroughly after each addition to ensure full incorporation.
06 - Blend in the room-temperature buttermilk, vanilla extract, and red food coloring until the mixture is smooth and evenly colored.
07 - Gradually add the dry ingredient mixture to the wet ingredients, mixing gently until just combined. Avoid overmixing to keep the cupcakes tender.
08 - Divide the batter evenly among the prepared liners, filling each about three-quarters full to cover the Oreo cookie at the bottom.
09 - Bake for 18 to 20 minutes, or until a toothpick inserted into the cupcake portion (avoiding the Oreo base) comes out clean. Allow the cupcakes to cool completely in the tin.
10 - Beat the softened cream cheese and butter together until smooth and creamy. Add the sifted powdered sugar and vanilla extract, then mix on medium speed until light and fluffy. Gently fold in the crushed Oreo cookies.
11 - Pipe or spread the frosting generously onto the fully cooled cupcakes. Garnish with additional Oreo crumbs or mini Oreo cookies if desired.