Preheat the oven to 250°F, line a 9x13 baking dish with parchment paper, and place the popcorn and nuts in the baking dish. Stir to combine.
Place the popcorn in the oven and cook for 20 minutes, stirring it half-way through. Let it rest for 15 minutes before heating. It will keep in an airtight container for 1 week.