Preheat oven to 200 degrees F. Line a jelly roll pan with parchment paper. Add popped popcorn and spread in an even layer.

Caramel: Melt butter in a large non-stick skillet over medium heat. Once melted, stir in brown sugar, corn syrup, and salt until smooth. Bring to a boil over medium heat, stirring occasionally. As soon as the caramel starts to gently boil, boil for 2 minutes, stirring constantly. Remove from the heat and stir in baking soda and vanilla

Drizzle caramel over popcorn. Toss gently with a spatula until the popcorn is evenly coated.

Bake at 200 degrees F for 45 minutes, stirring the popcorn every 15 minutes.

Store caramel corn in an airtight container at room temperature for to 2-3 weeks