Preheat your oven to 250°F (120°C).
In a large mixing bowl, combine Rice Chex, Corn Chex, pretzel twists, mixed nuts, chocolate-coated candies, and caramel popcorn.
In a small saucepan, melt the butter, brown sugar, and vanilla extract over medium heat until smooth and bubbly.
Pour the melted mixture over the dry ingredients and toss gently until everything is well coated.
Spread the coated mix onto a large baking sheet lined with parchment paper in an even layer.
Bake in the preheated oven for 1 hour, stirring every 15 minutes to ensure even coating and crispness.
Remove from the oven and sprinkle with kosher salt while still warm, if desired.
Allow the mix to cool completely before serving or storing in an airtight container.