Begin by popping your popcorn. Transfer the popcorn into a large mixing bowl, ensuring no un-popped kernels are left behind.
To the popcorn, add the rice square cereal, mini pretzel twists, and pecan halves. Gently stir until everything is evenly combined.
In a medium saucepan over medium heat, combine the brown sugar, butter, and light corn syrup. Stir continuously until the mixture begins to boil. Allow it to boil for about 4-5 minutes without stirring, until it reaches a rich golden color.
Remove the saucepan from heat and stir in the vanilla extract and baking soda. Be careful, as the mixture will bubble up.
Immediately pour the caramel over the popcorn mixture. Use a spatula or wooden spoon to gently fold the caramel into the mix.
Preheat your oven to 250°F (120°C). Line a baking sheet with parchment paper and spread the caramel-coated mix onto the sheet in an even layer.
Bake the mixture in the preheated oven for 45 minutes, stirring every 15 minutes for even coating.
Once baked, remove the snack mix from the oven and let it cool completely on the baking sheet. Once cooled, break it up into clusters and store it in an airtight container.
