Preheat the oven to 350°F (180°C). Line your muffin tin with cupcake liners.
In a large bowl, combine chocolate cake mix, eggs, vegetable oil, buttermilk, and baking soda. Mix until smooth.
Gently fold in the crushed Halloween Oreos.
Fill each cupcake liner about 2/3 full with the batter.
Bake for 18–20 minutes or until a toothpick inserted in the center comes out clean.
Let the cupcakes cool in the pan for 5 minutes, then transfer to a cooling rack.
While cupcakes cool, prepare the frosting: beat the butter (and cream cheese, if using) until creamy. Add powdered sugar gradually, then mix in vanilla extract and whipping cream until fluffy. Fold in crushed Oreos if desired.
Pipe or spread the frosting onto completely cooled cupcakes.
Decorate each cupcake with two Oreo halves (as wings) and two candy eyeballs to make spooky bat cupcakes. Add Halloween sprinkles and drizzle with melted chocolate if desired.
Serve and enjoy your spooky treats!