Preheat oven to 300 degrees F.
Line a large, rimmed baking pan (17x 12 –inches) with foil and spray lightly with cooking spray.
Spray a large mixing bowl (not plastic) with cooking spray and add popcorn (make sure to remove unpopped kernels) and nuts; set aside.
In a medium saucepan, combine chocolate morsels, corn syrup and butter. Cook over medium heat, stirring constantly, until mixture boils. Pour over popcorn; toss well to coat.
Spread in an even layer into prepared baking pan. Bake in preheated oven 40 minutes, stirring every 10 minutes.
Cool completely in pan. Break into pieces; store in an airtight container.
Clean-up tip: Soak saucepan before cleaning.
Recipe compliments of The Popcorn Board