How to Make It
Preheat oven to 275°F.
Stir together brown sugar, light corn syrup, unsalted butter, and sorghum syrup in a medium saucepan over medium. Cook, stirring occasionally, until butter is melted and sugar is dissolved, about 5 minutes.
Remove from heat; stir in blended Scotch whisky and baking soda. (Mixture should lighten significantly in color and begin to bubble.) Place unsalted popped popcorn in a large bowl; pour brown sugar mixture over popcorn in a slow, steady stream, stirring to coat completely.
Spread popcorn in a single layer on a baking sheet lined with parchment paper. Sprinkle evenly with flaky sea salt (such as Maldon). Bake in preheated oven 1 hour, stirring every 15 minutes. Remove from oven, and let stand at room temperature until completely dry, about 30 minutes.