Preheat your oven to 250 degrees F and line 2 large baking sheets with foil or parchment paper. Set aside.

In a large dutch oven add the oil and 3-4 corn kernels and heat over medium. Cover and wait 5-6 minutes for the kernels to pop. Remove from heat and add the rest of the corn kernels and sprinkle with sea salt. Cover again and place over low heat. The kernels should begin to pop after just a few seconds. Remove from heat once the popping has begun to subside. Transfer to a very large bowl.

To the bowl, add the chopped pretzels and pumpkin seeds. Toss to combine. Set aside.

In a large saucepan, add the the butter and melt over medium-low heat. Add the sugar, brown sugar, corn syrup, pumpkin pie spice and cinnamon. Whisk to combine. Bring the mixture to a boil and boil for 5 minutes without stirring. Remove from heat and stir in the vanilla extract and baking soda.

Pour a third of the sauce over the popcorn and toss to evenly coat. Add another third of the sauce, and again toss to evenly coat. Repeat this step once more.

Pour the popcorn onto the prepared baking sheets and even out. Place in the oven and bake for 1 hour and 15 minutes, stirring the popcorn every 15 minutes. Remove from heat and let cool completely.

Top with melted chocolate if desired. The popcorn will keep stored in an airtight container for about a week. Enjoy!