Crunchy and sweet, cinnamon popcorn is like caramel corn with a hint of cinnamon! The butter and sugar mellow out the bold cinnamon flavor of red hots, resulting in a buttery, lightly spiced treat.
Preheat the oven to 250 degrees Fahrenheit. Spray a large, deep roasting pan or a large oven-safe Dutch oven with pan spray and add 14 cups air-popped popcorn to it. Set aside.
Add ½ cup butter to a medium-sized heavy-bottomed pot and heat over medium heat.
Once the butter is melted, add 11 ounces red hots or cinnamon imperials,½ cup corn syrup, ½ cup granulated sugar, and ½ teaspoon salt. Cook over medium-low heat, stirring constantly, until the red hots are melted and the mixture is boiling.
Stop stirring and let it boil for 2 minutes. Turn off the heat and stir in ½ teaspoon baking soda. The red hot mixture can bubble up a bit at this stage, so make sure the pot you use has high sides, and you stir continuously until the bubbling up subsides.
Pour the red hot mixture over the popcorn and stir it as best you can until the popcorn is as evenly coated as you can get it.
Bake the cinnamon popcorn for 1 hour, stirring thoroughly every 15 minutes. Once the hour is up, turn out the popcorn onto sheet pans lined with parchment paper and let it cool completely before breaking into pieces and serving.