Caramel Popcorn

For caramel popcorn that is crispy, this one takes the prize. I will never get over my grandmother's handwriting.

6 qts popped popcorn

Bring the following to boil, stir constantly:
1 cup butter or margarine
2 cups brown sugar
1/2 cup light corn syrup

Boil 5 minutes without stirring, take off of heat and add:
1/2 tsp baking soda
1 tsp vanilla

Stir.

Pour over popcorn and stir.

Put p.corn on greased cookie sheet and bake for about 45 minutes at 250°, stirring every 15 min.
Remove from oven, let stand for 5 min, then break up and eat or store.