In a dutch oven, heat coconut oil until hot. (Test by putting one kernel in, and should bubble around the edges.) Add popcorn and swirl to coat.
Cover and cook, shaking pot, until all popcorn is popped. While doing this, occasionally let a little peep of air out so that popcorn doesn't steam. You can also use an air popper to make the popcorn if you'd like!
Set aside, and remove any unpopped kernels. Add nuts, if using.
In a high sided saucepan, add maple syrup and butter. Boil until mixture reaches 225 degrees F on a thermometer. Remove and add salt, cinnamon, and baking soda, stirring. Quickly pour mixture on popcorn and stir to fully coat.
Bake at 245 degrees F for 40 minutes, stirring once in the middle of baking, until dry. Store in a covered box or ziploc bag.