1/4 c. butter
1 c. brown sugar
1/2 c. light Karo syrup
2/3 c. sweetened condensed milk
1/2 tsp. vanilla
5 qt. popcorn

In saucepan, combine butter, sugar, and corn syrup. Bring to a boil over medium heat. Stir in condensed milk; simmer, stirring constantly, until mixture comes to soft ball stage (234 to 238 degrees). Stir in vanilla. Pour over popped corn and stir to coat.