Preheat oven to 250F degrees. Line a large baking sheet with parchment paper or a silicone baking mat. Set aside.
Place popped popcorn into a large bowl. Mix in chopped walnuts or pecans. Evenly, spread popcorn mixture onto prepared baking sheet. Set aside.
In a heavy saucepan, combine butter, brown sugar, and light corn syrup. On medium-high heat, bring to a rapid boil and boil for five minutes, stirring as necessary. Remove from burner and stir in vanilla extract and butter extract.
Pour caramel over popcorn mixture and stir to coat. Put in oven for 15 minutes. Take it out and stir it. Repeat this every 15 minutes for one hour.
Let cool on baking sheet. Once caramel corn is cooled, break up the popcorn and enjoy!
Notes
*Store caramel corn in an airtight container at room temperature for up to 7-10 days.