Preheat oven to 275 degrees and line 2 rimmed baking sheets with parchment paper.

Combine popped corn and cashews and set aside.

In a large stockpot combine the butter, brown sugar, corn syrup and vanilla, heat over medium-high heat, stirring occasionally until butter is melted and mixture is well combined

Cover and allow to cook without stirring until it become a light caramel color, 4 to 5 minutes.

Remove pot from heat, add baking soda.

Stir in the popped corn and the cashew mixture until well and evenly coated.

Transfer caramel corn to the two prepared cooking sheets, spreading out into a single layer on each.

Bake for 1 hour. Remove from oven and using a wooden spoon gently break up any clumps, and stir to coat fully with the caramel sauce.

Allow to cool completely.