Start by popping your popcorn using a stovetop method or air popper to have about 5 quarts ready.
In a medium saucepan, melt the butter over medium heat, then add brown sugar, corn syrup, and salt. Boil without stirring for about 4-5 minutes until golden.
Remove from heat and stir in vanilla extract and baking soda carefully, as the mixture will bubble up.
Combine the popped popcorn and shelled peanuts in a large bowl, then pour the caramel sauce over the mixture and gently fold to coat.
Preheat your oven to 250°F (120°C) and spread the coated popcorn on a baking sheet lined with parchment. Bake for about 1 hour, stirring every 15 minutes.
Let the popcorn cool completely on the baking sheet, then break into clusters and enjoy!
