Heat oven to 250 degrees. Pop popcorn and place in a large roasting pan and set aside. Melt butter in saucepan; stir in brown sugar, corn syrup, and salt. Bring to a boil, stirring constantly. Boil without stirring for 5 minutes. Remove from heat; stir in baking soda and vanilla. Pour over popcorn and stir well. Bake uncovered for one hour, stirring every 15 minutes. Break apart when cooled and store in a covered container.
Contributor: Anne Dickinson