Preheat oven to 270 F.
Place the popped popcorn in an oven safe bowl
In a saucepan melt the butter, brown sugar, corn syrup and salt
On Medium/High bring the to a boil and keep boiling until the temperature reaches 270
Remove from heat and carefully stir in cinnamon flavoring, then baking soda.
Working quickly, pour over popcorn stirring to coat.
To help the mixture stay warm so you can get an even coat place the bowl into the oven, stirring every 5 mins 3-4 times
Spread the popcorn out onto a pan and sprinkle with the cinnamon sugar mixture
Let the mixture cool, then break into pieces and serve