1. Place the cereal in a very large stainless steel bowl and set aside.
2. In a medium microwave-safe bowl, add the chocolate chips, hazelnut spread, peanut butter and butter. Microwave for a minute, then stir. Microwave 30 seconds longer and stir until smooth. Keep going until it's all melted, being careful not to burn. Stir in the vanilla and salt. Then pour the chocolate mixture over the cereal, tossing to evenly coat.
3. Spoon the mixture into a 2-gallon resealable ziptop bag along with the powdered sugar. Shake the bag until the cereal is evenly coated. Then add the pretzels and candies, seal and shake the bag again. Pour onto baking sheets to set/cool. Serve in bowls.