Preheat oven to 225 degrees
line an 11x17 baking sheet with parchment paper. Set aside
Place popcorn in a large stainless bowl. set aside
Mix brown sugar, corn syrup, butter and salt in a heavy 2 quart saucepan.
Stir constantly and bring to a boil over medium heat.
Once it comes to a boil, boil for 5 minutes without stirring. Remove from heat and stir in vanilla and baking soda.
Pour over caramel over popcorn. Place a second large stainless bowl over the popcorn, making a dome. Shake the popcorn, flipping the dome a couple times to thoroughly coat the popcorn.
Pour the caramel corn out on the parchment lined baking sheet. Place in oven and immediately turn the oven off!
Leave in oven for 15 minutes until caramel corn is a beautiful amber color.
Break apart. Store in an air tight container for up to one week.