01 - Preheat the oven to 350°F (175°C). Line a standard 12-cup muffin tin with paper cupcake liners.
02 - In a medium bowl, whisk together the all-purpose flour, unsweetened cocoa powder, baking soda, and salt. Set aside.
03 - In a large bowl, beat the vegetable oil and granulated sugar until well combined. Add the room-temperature egg, buttermilk, red food coloring gel, pure vanilla extract, and distilled white vinegar. Mix until the mixture is smooth and uniformly colored.
04 - Gradually add the dry ingredient mixture to the wet ingredients, mixing gently just until combined. Do not overmix. Gently fold in the roughly chopped Oreo cookies until evenly distributed.
05 - Divide the batter evenly among the cupcake liners, filling each about two-thirds full. Bake for 18 to 20 minutes, or until a toothpick inserted into the center of a cupcake comes out clean.
06 - Let the cupcakes cool in the muffin tin for 5 minutes, then transfer them to a wire rack to cool completely before frosting.
07 - In a mixing bowl, beat the softened unsalted butter and softened cream cheese together until creamy and smooth. Add the sifted powdered sugar and pure vanilla extract, then beat until the frosting is light and fluffy. Gently fold in the finely crushed Oreo cookies.
08 - Pipe or spread the cream cheese Oreo frosting generously onto the fully cooled cupcakes. Garnish with extra Oreo crumbs if desired.