Preheat the oven to 250 degrees F (120 degrees C). Spray a 10×15-inch baking pan with nonstick spray. Place popcorn and peanuts into a large metal bowl; set aside.

Combine sugar, butter, corn syrup, and cocoa together in a saucepan over medium-high heat; bring to a boil, stirring continuously, and cook for 2 minutes. Stir in vanilla, then pour over popcorn in the bowl. Stir until popcorn is well-coated; spread on the prepared pan.

Bake in the preheated oven, stirring several times, for 30 minutes.

Remove popcorn from the oven; allow to cool to room temperature to crisp up. Break into small clumps and store in an airtight container.