1 cube of butter, melt
1/4 c. Karo
1 c. brown sugar
1/2 tsp. salt

Cook 4 minutes on high power. Add 1/2 teaspoon baking soda. Put 1 gallon popped popcorn in a brown paper bag. Pour cooked mixture over top. Shake. Cook in microwave 1 minute. Shake. Cook in microwave another minute. Shake and cook for 1/2 minute. Pour out and spread to cool.