In a large, greased, roasting pan, combine popcorn and nuts. In a large, heavy saucepan combine chocolate chips, corn syrup and butter. Cook over medium heat until mixture boils, stirring constantly. pour over popcorn toss well to coat. Bake in a preheated 150ºC oven for 45 minutes stirring frequently. Cool completely. Store in an airtight container for up to two weeks. Makes about 14 cups.