Creating Halloween Oreo Cake Bars is a breeze when you follow these simple steps:

1. Preheat Oven: Preheat your oven to 350°F (175°C) and grease a 9×9-inch baking pan.
2. Mix Dry Ingredients: In a large bowl, whisk together the flour, sugar, cocoa powder, baking soda, and salt until well combined.
3. Combine Wet Ingredients: In another bowl, mix the melted butter, eggs, vanilla extract, and milk until smooth.
4. Combine Mixtures: Gradually add the wet ingredients to the dry ingredients, stirring until just combined.
5. Add Oreos: Fold in the crushed Oreo cookies gently, ensuring they are evenly distributed throughout the batter.
6. Bake: Pour the batter into the prepared baking pan and spread it evenly. Bake for 25-30 minutes or until a toothpick inserted in the center comes out clean.
7. Cool: Remove from the oven and let the cake cool in the pan for 15-20 minutes. Then, transfer it to a wire rack to cool completely.
8. Prepare Frosting: In a medium bowl, beat the softened cream cheese and powdered sugar together until smooth. Fold in the whipped topping until well combined.
9. Frost the Cake: Once the cake is completely cool, spread the cream cheese frosting evenly over the top.
10. Decorate: Top with additional crushed Oreos and Halloween-themed sprinkles for a festive touch.
11. Slice and Serve: Cut into bars and enjoy your Halloween Oreo Cake Bars!

These steps will guide you seamlessly through the process of creating these incredible treats!