Caramel Corn

3/4 cup butter
1 1/2 cups brown sugar
1/3 cup corn syrup
3/4 tsp salt
1/4 tsp baking soda
1/2 tsp vanilla
5-6 quarts popped popcorn (2/3 cup unpopped)

Preheat oven to 250 F. Place popped popcorn on 2 cookie sheets, making a pile in the center.
Melt butter in saucepan over medium heat. Add sugar, corn syrup, and salt. Bring to a boil, stirring constantly. Boil undisturbed 4 minutes. Remove from heat and stir in soda and vanilla. Pour over popcorn and stir to coat.

Bake for 1 hour, stirring every 15 minutes. After the first 15 minutes the caramel will be quite soft and can be distributed more evenly over the popcorn, it will be more brittle and not adhere as well after that. Let cool. Store in an airtight container.