1Pop popcorn. Dump each batch into a large enamel roasting pan (turkey size) that has been treated with food release spray.
2In a heavy 3 qt. saucepan melt the butter with the brown sugar, corn syrup, and salt. Over medium heat bring the sauce to a hard, rolling boil. Boil 5 minutes.
3Quickly stir in baking soda -- caramel will foam up.
4Immediately pour the caramel over the popcorn. Mix carefully and thoroughly, until all kernels are coated.
5Bake at 200* for 1 hour, stirring well every 15 minutes.
If you like, you can stir in nuts at the last 15 min.
Remove from oven. Cool and serve.
6NOTES: You may use light or dark brown sugar, and light or dark corn syrup -- it changes the flavor, so experiment to find your favorite combination :)
Store in another room -- it's hard to stop eating it!