In a large microwave safe bowl, microwave the chocolate chips, Nutella and butter in 30 second intervals, mixing until smooth. Mix in the vanilla.
Pour in the Chex cereal and slowly mix until the cereal is coated in chocolate.
Add the powdered sugar to a large ziplock bag. Scoop the chocolate Chex cereal into the bag and seal. Shake until the cereal is completely covered in powdered sugar.
Line a baking sheet with parchment paper. Pour the cereal mixture overtop in an even layer. Allow to cool until the chocolate has hardened.