1-First, preheat your oven to 300°F (150°C) to get that perfect baking temperature. Line a large baking sheet with parchment paper or a silicone mat for easy cleanup and even heating. Pop the 1/2 cup of unpopped popcorn kernels using an air popper into a large bowl, yielding around 16 cups of fluffy popcorn as your base.

2-Next, in a small saucepan over medium heat, melt 1 cup salted butter along with 1 cup light brown sugar, 1/3 cup light corn syrup, and 1 teaspoon of the kosher or sea salt. Stir occasionally until the mixture reaches a boil, then stop stirring and let it boil for exactly 4 minutes to achieve that silky caramel consistency.

3-After boiling, remove the saucepan from the heat and let the caramel mixture cool undisturbed for 2 minutes. This step helps stop the boiling and prevents any splatters. Pour the cooled caramel over the popped popcorn in the large bowl and stir thoroughly to coat every piece evenly, ensuring that delicious flavor reaches all the kernels.

4-Transfer the caramel-coated popcorn to the prepared baking sheet, spreading it into a single layer. Sprinkle the remaining 1/2 to 1 teaspoon of kosher or sea salt over the top, adjusting to your taste. Bake in the preheated oven for 30 minutes, stirring every 10 minutes to promote even cooking and prevent burning. Once done, remove the tray from the oven and let the salted caramel popcorn cool completely on the parchment-lined surface before serving.