Begin by popping the popcorn. You can either use an air popper or stovetop method. If using the stovetop, heat a large pot over medium heat and add a tablespoon of oil. Once hot, add popcorn kernels, cover, and shake the pot until popping slows down. Once popped, set aside in a large mixing bowl.
In a medium saucepan, combine the unsalted butter, light corn syrup, brown sugar, and salt. Cook over medium heat, 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 and baking soda. The mixture will bubble up, so be careful! Stir until smooth and well combined.
Pour the caramel sauce over the popped popcorn in the large mixing bowl. Quickly add the pretzels, peanuts, Reese’s Pieces, and Reese’s Peanut Butter Cup Minis. Using a spatula, gently fold everything together until all the ingredients are coated in caramel.
Preheat your oven to 250°F (120°C). Spread the popcorn mixture evenly onto a baking sheet lined with parchment paper. Bake for 30 minutes, stirring every 10 minutes to ensure even coating.
Once baked, remove the tray from the oven and let the mix cool completely. Once cooled, break it into pieces and serve or store in an airtight container.
