This is a recipe that I have used for 25 years and is one of the best and easiest that I have ever used. No need to use a candy thermometer. This can be stored for up to a week but it never lasts that long when I make it.
1Preheat oven to 250 degrees.
Coat a large jelly roll pan with crisco or cooking spray.
Pop the popcorn and remove the unpopped kernels.
Place the pocorn, nuts and pretzels in a large bowl.
2Combine Sugar, corn syrup, and butter in a medium or large heavy bottomed sauce pan.
Melt the above ingredients on high, bring to a boil. Then reduce to medium heat.
Cook 4-5 minutes, stirring 2-3 times with a wooden spoon to scrape down the sides of the pan keeping the mixture bubbling up. Be careful, the mixture will burn you if it boils over onto you.
3Remove from heat: stir in vanilla, baking soda and salt. Stir well to combine the baking soda thoroughly. The mixture will change color slightly after adding the baking soda. Pour the mixture over the popcorn in the bowl in a steady stream, stirring to coat. Work quickly as it will begin to set up as soon as it starts to cool. Again be careful, the mixture is very hot.
4Spread popcorn mixture into prepared jelly roll pan.
Bake at 250 degrees for 45 minutes stirring the mixture every 15 minutes.
Remove from the oven, stir to break up any large clumps. Again be careful,Popcorn will be hot if you are using your hands. Cool for several minutes (we can't leave it alone long enough to cool).
5Can be stored in an airtight container for up to one week (it never lasts that long at my house). Let the popcorn cool completely before storing.