Prepare the Pan: Line a 9×9 inch baking pan with parchment paper, leaving an overhang on two sides for easy removal. Lightly grease the parchment paper with non-stick spray.

Combine Dry Ingredients: In a very large mixing bowl, combine the crispy rice cereal, chopped cookies, broken pretzels, and 1 cup of the Halloween candy. Set aside.

Melt Wet Ingredients: In a medium saucepan over low heat, combine the peanut butter, chocolate chips, and butter. Heat, stirring constantly, until the mixture is completely smooth and melted. Remove from heat and stir in the vanilla extract and salt.

Combine and Press: Pour the warm chocolate and peanut butter mixture over the dry ingredients. Use a sturdy spatula to fold everything together until all the dry components are evenly coated.

Transfer to Pan: Pour the mixture into the prepared baking pan. Spread it out into an even layer. Use the bottom of a flat glass or measuring cup to press the mixture down very firmly and compact it.

Add Toppings: Immediately sprinkle the remaining ½ cup of Halloween candy over the top and press down lightly so they adhere.

Chill: Refrigerate the bars for at least 2 hours, or until completely firm.

Slice and Serve: Once set, use the parchment paper to lift the entire block of bars out of the pan. Place on a cutting board and slice into 16 squares. For a festive touch, melt white chocolate chips and drizzle over the bars before slicing.

Store: Keep bars stored in an airtight container in the refrigerator for up to one week.