Preheat oven to 250°.
Place brown sugar, maple syrup, and butter in a saucepan and bring to a boil for 1 minute.
Remove from heat and stir in maple flavor.
Immediately stir in baking soda.
Spread onto baking sheets in a single layer.
Bake for 1 hour, stirring every 20 minutes.
Remove from the oven and add sea salt, to taste.
Spread out caramel corn and allow to cool.