Pour Chex cereal into a large mixing bowl and set aside.
In a double boiler or microwave-safe bowl, melt white chocolate and butter together in 20-second intervals, stirring until smooth.
Stir in pumpkin purée, vanilla, pumpkin pie spice, and a pinch of salt. The mixture should be silky and fragrant.
Pour over the Chex cereal and gently toss until every piece is coated.
In a large zip-top bag, mix the powdered sugar and extra pumpkin spice. Add the coated cereal, seal, and shake until fully covered in spiced sugar goodness.
Spread out on parchment paper and pop in the fridge to cool completely.
Enjoy!