Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners. In a large mixing bowl, combine the chocolate cake mix with the eggs, oil, and water. Use an electric mixer for about 2 minutes until smooth. Pour the batter into prepared liners, filling each about two-thirds full. Bake for 19-23 minutes until a toothpick comes out clean.

Once the cupcakes are baked, cool them in the muffin tin for 5 minutes, then transfer to a wire rack to cool completely, about 30 minutes.

After cooling, fill a piping bag with chocolate frosting. Pipe from the outside edge in a circular motion to create a generous swirl on each cupcake.

Cut each Oreo in half and stick two halves into the frosting on each cupcake at an angle for bat wings. Position a pair of candy eyes on top.

Optional: Chill the decorated cupcakes in the refrigerator for about 5 minutes for a polished finish.