Best Carmel Popcorn!!

1 cup butter
2 cups brown sugar
½ cup corn syrup
1 tsp. salt
½ tsp. baking soda
1 tsp. vanilla
5 quarts popped popcorn

1. Preheat oven to 250 degrees. Place popped popcorn in very large bowl.
2. In saucepan, melt butter over medium heat. Stir in brown sugar, corn syrup and salt. Bring to a boil, stirring constantly. Boil without stirring 4 minutes. Remove from heat and stir in soda and vanilla. Pour over popcorn, stirring to coat.
3. Place in 2 shallow baking dishes and bake in preheated oven, stirring every 15 minutes for about 45 minutes. Remove from oven and let cool completely on wax paper before breaking into pieces."