Warning: do not walk away from your caramel because it will probably burn the second you walk away from it (trust me).
In a heavy bottomed saucepan over medium heat, add the sugar and stir every 1-2 minutes or so until it begins to melt (the sugar will start to clump up before melting).
Once the sugar is completely melted and golden in color, immediately remove from the heat and stir in the butter until combined (don’t be scared if it bubbles a lot).
Add in the heavy cream and salt and mix until fully combined and smooth.
Pour the caramel into a glass jar to cool. Can be stored in the fridge for up to a month!
Preheat the oven to 275°F and line a baking sheet with parchment paper.
Using an air popper, pop the popcorn according to manufacturer instructions (see notes for stove-top popcorn), then dump onto the parchment lined baking sheet.
Drizzle the caramel over top of the popcorn and toss until evenly coated. You can add as little or as much of the caramel as you want!
Bake at 275°F for 15-20 minutes, stirring every 5 minutes, until the caramel has formed a semi solid shell on the popcorn.
Remove from the oven and let cool.
Store in an airtight container at room temperature for up to 5 days.
Stove-top popcorn: In a large stock pot or dutch oven (with a lid) heat the ¼ cup of vegetable oil or coconut oil and 3 popcorn kernels over medium heat (don't forget to put the lid on). Once those kernels pop (about 2-3 minutes) add in the rest of the popcorn kernels and give the pot a shake to evenly coat the kernels in oil. Cover the pot and continue to cook the popcorn, giving the pot an occasional shake to ensure it doesn't burn. Once the kernels start to pop, watch closely until the popping sounds slow down to one pop every 2-3 seconds. Remove the lid and dump the popcorn into a large serving bowl.