- 1 (3½-ounce) package plain (unbuttered natural flavor) microwave popcorn
- 1 cup packed light brown sugar
- ¼ cup light corn syrup
- 6 tablespoons unsalted butter, melted
- ¼ teaspoon salt
- 2 teaspoons vanilla extract
- ½ teaspoon baking soda
- 1 cup lightly salted peanuts (extra large, if available), roughly chopped
- Heat the oven to 250°F. Line a rimmed baking sheet with parchment paper and set aside.
- Pop the popcorn according to the package instructions. Coat a large mixing bowl with nonstick cooking spray and transfer the popcorn from the bag to the bowl, then set the bowl aside.
- Whisk the sugar, corn syrup, butter, salt, and 2 tablespoons of water in a pot and bring to a simmer over medium-high heat. Continue to simmer, stirring often, until the mixture reads 250°F on a digital thermometer, 3 to 4 minutes. Turn off the heat and whisk in the vanilla and the baking soda. Immediately pour the hot mixture over the popcorn. Use a rubber spatula to gently fold the caramel into the popcorn until all of the popcorn is coated. Gently stir in the peanuts and transfer the mixture to the prepared baking sheet. Bake for 1 hour, stirring every 20 minutes. Remove from the oven and place on a cooling rack for 20 minutes. Gently break up the popcorn and serve immediately, or store in an airtight container for up to 5 days (less if it’s hot and humid).