Caramel Popcorn

4 bags popped microwave buttered popcorn
1 cube butter
1 cup corn syrup
2 1/2 cups brown sugar
1 can sweetened condensed milk
Boil everything but the milk for 1 minute. Add milk. Bring to boil again. Add 1 tsp vanilla. Remove from heat. Pour over popcorn.

(I usually 1/2 the recipe then make the other half a few days later)