Ingredients:

6-10 quarts unsalted, popped popcorn
1 c. butter
2 c. dark brown sugar
1/2 c. corn syrup

1 tsp. salt
1/2 tsp. baking soda
1 tsp. vanilla
1/2-3/4 c. dry roasted peanuts, optional

Directions:

Put popped popcorn in a large shallow pan, such as a broiler pan.  
While making the syrup, keep the popcorn warm in a 200º oven.
Bring to a boil the butter, sugar, corn syrup & salt.
Cook 5 minutes stirring constantly.
Remove from heat & stir in baking soda & vanilla.
Pour the syrup over the popcorn & mix very well.
Return to a 250º oven for 1 hour.
Stir every 10-15 minutes.  Add nuts last 10 minutes of baking time.
Spread out to cool.
Store in a tightly covered container.