Prepare a baking sheet by lining it with a silicone liner or parchment paper; set aside. Chop or break any larger candies, cookies, or pretzels; set aside.
Melt the vanilla candy bark (or white chocolate) as directed on package. If heating in the microwave, use 50% power to prevent overheating the candy/chocolate. Pour about half of the melted chocolate onto the lined baking sheet, then spread about 1/4 inch thick.
Working quickly, add an assortment of pretzels, cookie pieces, and candy corn (or other candies) in a single layer. Pour the remaining melted chocolate on top of the pretzels and cookies, then add additional toppings, including sprinkles. Set aside and allow the chocolate to cool fully. You can place the entire baking sheet in the freezer for 10 minutes to speed up the process.
Once the chocolate is fully set and cool, break the candy bark into pieces. Store Halloween Candy Bark in an airtight container for up to a week.