CARAMEL PUFF CORN 1 c. butter 2 c. brown sugar 1/2 c. light Karo syrup. Boil ingredients for 5 minutes and then add 1/2 teaspoon baking soda. Pour this mixture over 2 bags of puff corn (hulless popcorn) then spread in a deep roasting pan. Bake at 250 degrees for 1 hour--mixing/stirring every 15 minutes. Spray with Pam beforehand.