This is the best caramel corn recipe I've ever eaten. I received the recipe from my good friend Shirley in Southern California (really Southern, as almost on the Mexican border!) I frequently take it to bake sales, putting two ounces each into zipper or zip-lock sandwich bags. Sorry, I don't measure it in a measuring cup; I use my kitchen scale. Two ounces fills a sandwich bag about two-thirds full. One recipe makes 13-15 bags. It is always the first item to sell out at bake sales. And I'm frequently asked for the recipe. Enjoy!
1. Remove all "Old Maids" (unpopped corn kernels) and discard.
2. Put the popped corn into an 8-10 quart large bowl. Add the nuts to the popcorn, if desired. Toss.
3. Set out two ungreased half-sheet pans (13" x 18" x 1") or jelly roll pans (10 1/2" x 15 1/2" x 1/2").
4. Move two oven racks into the middle third of the oven. Preheat oven to 200 degrees.
5. Stir together in a 6 to 8 quart heavy sauce pan the butter, brown sugar, salt, and corn syrup. Bring to a boil over medium-high heat, stirring constantly. Lower the heat to medium-low so the syrup boils slowly but constantly for 5 minutes. You do not need to stir the syrup during this time. Remove from heat.
6. Be aware that when you stir in the soda, the syrup becomes very foamy and increases in volume by one-third to one-half! Quickly stir in baking soda thoroughly with a wooden spoon, stirring up the syrup from the bottom of the pan so that it all becomes foamy.
Pour the foamy syrup from the pan over the popcorn and quickly stir until the popcorn is evenly and completely coated.
Pour the coated popcorn evenly into the two pans. Stagger the pans, long ends front-to-back, in the oven, if possible.
Bake for 15 minutes. Remove one pan from the oven and turn the caramel corn over using a metal spatula. Remove the other pan from the oven and put the first pan in its place. Turn over the caramel corn and return the second pan to the oven.
Repeat turning the caramel corn over three more times for a total baking time of one hour.
After the caramel corn has been turned over for the fourth (and last) time, let it cool until it can be handled. Break the large pieces apart with your hands, then let it cool completely. Store in a tightly closed container
If your caramel corn remains sticky, either the syrup didn't boil long enough, margarine was used instead of butter (it has a higher moisture content), the caramel corn was put into the container before it was completely cool, or the humidity was too high. The texture should be very dry and crunchy.