Preheat your oven to 350°F (175°C). Line a large baking sheet with parchment paper.
In a large mixing bowl, combine the pecans, almonds, pretzels, and Rice Chex cereal. Stir to mix evenly.
In a saucepan, melt the unsalted butter over medium heat.
Add the brown sugar and corn syrup to the melted butter, stirring constantly until the mixture comes to a boil. Allow it to boil for 2 minutes without stirring.
Remove the saucepan from heat and stir in the vanilla extract, baking soda, and salt. The mixture will bubble up.
Pour the butter mixture over the dry ingredients in the large bowl. Using a rubber spatula, gently fold the mixture together until everything is well coated.
Spread the coated mix evenly on the prepared baking sheet.
Bake in the preheated oven for 20-25 minutes, stirring every 10 minutes to ensure even baking.
Remove from the oven and allow to cool completely on the baking sheet.
Once cooled, break the mix into clusters and store in an airtight container until ready to serve.