Place popcorn in a large bowl coated with cooking spray; set aside. Butter the sides of a small heavy saucepan; add the brown sugar, butter, corn syrup, molasses, ginger, cinnamon and salt. Bring to a boil over medium heat, stirring constantly. Boil without stirring for 5 minutes.
Remove from the heat; stir in baking soda (mixture will foam). Stir in vanilla. Quickly pour over popcorn and mix well.
Transfer to 2 greased 15x10x1-in. baking pans. Bake at 250° for 1 hour, stirring every 10 minutes. Remove from pans and place on waxed paper to cool. Store in an airtight container.