Preheat the oven to 250 degrees F. Pop the corn according to package directions and transfer to a large bowl. Set aside. In a medium saucepan, combine the sugar, butter, salt, corn syrup, vanilla bean and cacao nibs. Bring to a boil, stirring occasionally, over medium heat.
Pour the caramel over the popcorn, tossing to coat evenly. Divide the caramel corn between 2 parchment-lined sheet pans. Bake, stirring every 15 minutes, until the popcorn is sticky and caramelized, about 1 hour. Cool the popcorn on sheet pans, stirring often for the first few minutes (so it doesn't stick together). Store in an airtight container up to 5 days.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.
Recipe courtesy Elise Fineberg, Prospect, San Francisco, CA