14 cups popped corn, about ½ cup unpopped kernels
1 ¾ cups roasted peanuts
1 ½ cup firmly-packed dark brown sugar
½ cup light corn syrup
1 ½ cup butter
1 tablespoon molasses
½ teaspoon salt, plus more for sprinkling
1 ½ teaspoons vanilla extract
1/2 teaspoon baking soda
Preheat oven to 200 degrees F. Lightly spray two large sheet pans with oil. Set aside.
Spray a large bowl with oil and place the popped popcorn and peanuts in it.
In a heavy-bottomed medium saucepan over medium-low heat, combine brown sugar, corn syrup, butter, and molasses. Stir until smooth and melted. Increase heat to medium, stirring constantly until the caramel sauce begins to boil. Set a timer to boil for 5 minutes only, stirring occasionally during this phase. Let boil until the time is up or the temperature reaches 235 degrees F. on your candy thermometer. Immediately remove from heat and carefully stir in the vanilla extract, then the baking soda. Carefully, pour the hot caramel syrup over popcorn, stirring to evenly coat.
Divide the popcorn evenly among the two prepared sheet pans. Place in the oven and bake for about 60 minutes, stirring every 15 minutes. Test for doneness by taking a piece of caramel corn off the sheet pan and letting it cool to room temperature. If it's hard and crunchy, it's done.
Remove from the oven and let cool. Once cool, break apart any large clumps with your hands.
Store in airtight container at room temperature.