Baked Caramel Corn

From Jolly Time Popcorn's website. I made this last weekend and I cannot stop eating it. It's good.

• Ready In: 1 hr 5 mins
• Serves: 24

Ingredients

• 24  cups  popped popcorn
•  nonstick cooking spray
• 1  cup butter or 1  cup margarine
• 2  cups  firmly-packed brown sugar
• 1⁄2 cup light corn syrup
• 1  teaspoon salt
• 1⁄2 teaspoon baking soda
• 1  teaspoon vanilla

Directions

1. Preheat oven to 250°F Coat the bottom and sides of a large roasting pan with nonstick cooking spray. Place popped popcorn in roasting pan.
2. In a heavy pan, slowly melt butter; stir in brown sugar, corn syrup and salt. Heat to a boil, stirring constantly; boil without stirring for 5 minutes. Remove from heat; stir in baking soda and vanilla. Gradually pour over popped popcorn, mixing well.
3. Bake for 1 hour, stirring every 15 minutes. Remove from oven, cool completely. Break apart and store in tightly-covered container.