Preheat oven to 225ºF. Spray a 15 x 10-inch baking pan with cooking spray.

Combine popcorn and nuts in baking pan and place in oven to keep warm.

Heat chocolate, brown sugar, corn syrup and butter in a 2-quart saucepan over medium heat until boiling, stirring occasionally

Boil 5 minutes, stirring constantly.

Remove from heat and immediately stir in baking soda.

Pour chocolate-caramel mixture carefully over popcorn and nuts.

Use cooking spray-coated tongs or a spatula to toss the popcorn and chocolate-caramel mixture.

Bake popcorn for 60 minutes stirring popcorn about halfway through.

Let popcorn cool completely on wire rack.

Break popcorn into bite-sized pieces and store in an airtight container.