1. Preheat oven 350F.
2. Airpop popcorn, if desired, into large metal bowl. The bagged stuff works just fine, too, if you’d rather use that. Sprinkle nuts over top (optional).
3. Stir brown sugar, butter, corn syrup and salt in a medium saucepan over medium heat, until bubbly. Cook 5 more minutes, stirring occasionally. Remove from heat and stir in baking soda.
4. Pour the sauce over the popcorn in the metal bowl (you can also divide the popcorn between a couple of cake pans, if you prefer). Stir until everything is well-coated.
5. Bake for 30 minutes, stirring after 15 minutes. Enjoy hot (yum!), or allow to cool and then store in an airtight container or bags.

This is great to pack for travel, games, school, gifts, you name it. It rarely lasts more than a day around here, but it keeps well at least a week if you store it airtight, so you can make it ahead of time!