1 cup butter
2 cups brown sugar
1/2 cup Karo syrup
1 tsp salt
1/2 tsp baking soda
1 tsp vanilla
6 qts popped corn

Melt butter in large pan. Stir in sugar, salt, and Karo syrup. Bring to boil while stirring constantly. Once mixture comes to a boil, boil for 5 minutes without stirring. Remove from heat and stir in baking soda and vanilla. Pour over popped corn and stir to coat. Place popcorn on baking pans. Bake at 200 degrees for 1 hour and then turn up oven to 250 degrees and bake for 45 minutes more. Stir every 15 minutes.