Preheat your oven to 250°F (120°C).
In a large mixing bowl, combine Rice Chex, Corn Chex, and pretzel sticks, mixing well to ensure even distribution.
In a separate microwave-safe bowl, combine white chocolate chips and cinnamon. Microwave for 30-second intervals, stirring in between, until fully melted and smooth.
Pour the melted chocolate mixture over the Chex and pretzel mix. Stir gently until everything is evenly coated.
Fold in the candy corn, M&M's, and half of the Halloween sprinkles. Mix until just combined.
Spread the mixture out evenly on a parchment-lined baking sheet.
Bake in the preheated oven for 30 minutes, stirring every 10 minutes to keep the mix evenly toasted.
Remove from the oven and let the Chex mix cool completely. Once cool, add the remaining sprinkles.