Caramel Corn
From thekitchn.com

Make caramel corn, make new friends. For some variation, you can substitute cereal, pretzels, and peanuts for some of the popcorn to make a caramel party mix.

10-12 cups plain popped popcorn (from ½ cup unpopped kernels)
¾ cup unsalted butter
1 cup packed brown sugar
1 tsp vanilla
1 tsp kosher salt
¼ tsp baking soda

1. Preheat oven to 250⁰. Line 2 baking sheets with parchment paper or a non-stick liner.
2. Melt the butter in a saucepan over medium heat. Mix in the sugar until completely moistened, and increase the heat to medium to bring the mix to a boil. Once the sugar reaches a boil, let it go for 3-4 minutes while scraping the bottom of the pan with a heatproof spatula to keep it from burning.
3. Remove from heat and add vanilla, salt, and baking soda, and stir until smooth.
4. Pour the caramel sauce over the popcorn while stirring the popcorn. Stir until all of the popcorn is coated. Spread the caramel corn out over the two trays in an even layer and bake for 1 hour, stirring every 15 minutes or so.
5. Let the caramel corn cool completely and serve immediately, or store in an airtight container.