Preheat oven to 300°. Line a large baking sheet with parchment paper and lighty spray with nonstick spray.
In a large bowl, combine the Honeycomb cereal, mini pretzels, and nuts.
In a small saucepan over medium heat, melt the butter. Add the honey and stir until smooth and bubbly (2-3 minutes.) Remove from heat and stir in vanilla extract, salt, and cinnamon.
Pour the warm honey butter mixture over the dry ingredients. Gently toss to coat. It will be sticky but trust the process!
Spread the mixture on the parchment lined baking sheet in an even layer. Bake approximately 20 minutes, stirring halfway through.
Immediately after removing from the oven, give a gentle stir with a spatula to break it up and prevent clumping as it cools. Let the mix cool completely on the tray, stirring occasionally. The mix will crisp up as it cools.
Once completely cool the mix can be stored in an airtight container for up to a week (I doubt you'll have any left to store though!)
