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.
To make the caramel, place the butter, sugar, corn syrup, and water in a medium saucepan and melt together on medium-low heat. When it comes to a boil, stir a couple of times until it’s blended, then let it cook without stirring until the temperature is 260°F on a candy thermometer, about 6-8 minutes.
(If you don’t have a thermometer, you can test this way: Fill a glass with cold water, and after 6 minutes, spoon a bit of the caramel into the water. If it forms a soft ball, it’s ready, otherwise continue to cook a minute or so more, testing again.)
Meanwhile, in a separate bowl stir together the baking soda, cinnamon, chipotle chile powder, cumin, and salt.
When the caramel reaches the correct temperature, remove from the heat and stir in the spices and vanilla. The caramel will become thicker and foamy.
Immediately pour the caramel evenly over the popcorn and nuts, then working with two forks, blend the caramel evenly with the popcorn.
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.