I could eat this salted caramel popcorn every day of my life. With crunchy peanuts and the easiest homemade caramel, it's an absolutely addictive snack that comes together with just a few minutes of prep. And, it lasts for weeks so you can make it well in advance!
Preheat the oven to 225°F (107°C). Line a full sheet pan with parchment paper. Mix the popcorn and peanuts on the prepared sheet pan and set aside.
Add the unsalted butter, brown sugar, and corn syrup to a heavy bottomed saucepan. Set the pot on the stove over medium heat and cook, stirring constantly, until the caramel is smooth and comes to a boil. Clip a candy thermometer to the side of the pot (make sure it's not touching the bottom of the pot!) and bring the caramel to a boil. Boil the caramel, without stirring, for 4-5 minutes, or until it reaches 235°F (112°C).
Remove the caramel from the heat and quickly stir in the Kosher salt and vanilla extract. (Be careful, it will bubble up.) Then, mix in the baking soda. The caramel should nearly double in size, lighten in color, and become airy. That's what you want, it helps coat the popcorn more evenly!
Drizzle the caramel sauce over the popcorn-peanut mixture. Use a rubber spatula to very gently toss the caramel with the popcorn and peanuts until it's well-coated. Be patient, it takes quite a few stirs to completely coat everything! Spread the popcorn into an even layer.
Bake the popcorn for 1 hour, tossing it every 15-20 minutes to continue coating the popcorn evenly with the caramel sauce. Once the popcorn is baked, garnish it with flaky salt, to taste. Let the popcorn cool for 30-60 minutes, or until it's completely dry and crisp.
Break the popcorn apart with your hands and enjoy! Store an leftovers in an airtight container for up to 2 weeks.
Notes
If you don't have a full sheet pan, you can also use two half sheet pans. Just divide the popcorn, peanuts, & caramel sauce between the 2 sheet pans, following the rest of the recipe as written.You can make the caramel without a candy thermometer, but I wouldn't necessarily recommend it. If the caramel cooks too long, it'll be impossible to toss with the popcorn!Make sure you're using plain popcorn with no added salt or seasonings. I use air-popped popcorn, but if you don't have an air popper, you can make it on the stove. Or, use plain microwaved popcorn. About 1/3 cup of popcorn kernels will yield 10 cups.I used Diamond Kosher salt in this recipe. If you use Morton Kosher salt, start with 1/2 teaspoon.Don't worry if you don't coat all of the popcorn and peanuts when you're tossing everything together. The caramel will continue to melt in the oven, which will allow you to coat all of the popcorn during the baking process.If the caramel is still a bit soft after it's cooled, you can always pop it back in a 225°F (107°C) oven for another 15-30 minutes, as needed.To add a chocolate drizzle, I would use milk, dark, or white chocolate candy melts. Drizzle the chocolate on the popcorn after it's completely cooled and crisped.