Preheat the oven to 250 degrees F and line a large baking sheet with parchment paper.
In a large pot, add the olive oil and corn kernels. Place over medium heat and cover with a tight lid. The kernels will start popping after a few minutes. Once popping slows, check to make sure most of the kernels have popped, then place the lid back on and remove from heat.
While the popcorn is popping, make the caramel. In a medium saucepan, combine the brown sugar, butter, heavy cream, and 1 tbsp salt.
Place over medium heat and bring to a boil, stirring frequently. Continue boiling until it reaches 250 degrees F. Remove from heat and stir in the vanilla. Allow to cool for a few minutes.
Remove two heaping cups of the popcorn and set aside. Spread the rest of the popcorn onto the prepared baking sheet. Pour the caramel on top and use a rubber spatula or your hands to gently mix until evenly coated.
Spread the popcorn back into an even layer, then bake for 30 minutes, stirring every 10 minutes.
Once the popcorn comes out of the oven, mix in the reserved plain popcorn and ½ tablespoon salt.
Allow to set for about 15 minutes, then break apart & enjoy!