Preheat oven to 200ºF.
In a large bowl (or two), combine popcorn and peanuts; stir and set aside.
Grease the bottom and up the rims of two large baking sheets with flavorless oil; set aside.
In a medium saucepan over medium-high heat, add butter, brown sugar, corn syrup, molasses and ¼ tsp. salt; stir until the butter and sugar are melted.
Attach a candy thermometer and let the mixture simmer, undisturbed, until the temperature reaches 250ºF, about 5 to 6 minutes.
Remove from the heat and stir in vanilla and baking soda. Immediately pour it over the popcorn-peanut mixture; stir to coat evenly.
Divide the popcorn mixture between the two prepared baking sheets and spread evenly into a single layer. Sprinkle salt on top.
Transfer to the preheated oven and bake until the mixture is drier, about 30 minutes.
Remove from the heat and let the popcorn cool completely, about 2 minutes, before transferring to a bowl or bucket.