Prep: Pop 3 quarts (1/3 cup of kernels) of popcorn and place on a lined baking sheet or parchment paper. Mix in the mixed nuts. Preheat the oven to 250˚F.

Caramel Sauce: Combine the remaining ingredients (except for the vanilla) in a 1 1/2 quart sauce pan. Bring to a boil over medium heat stirring constantly. When the liquid reaches 300˚F - 310˚F (hard crack stage) remove it from the heat and stir in the vanilla.

Assemble: Pour the (very hot) liquid over the popcorn and carefully toss to coat well. Place cookie sheet in preheated oven and bake for 15 minutes, stirring every 5 minutes. Let cool.

Serve: Break apart once fully cool (about 20 minutes) and store in an airtight container for up to one week at room temperature.