Heat the oven to 300°. Spray a large rimmed baking sheet with cooking spray. In a large bowl, mix the popcorn and peanuts. Set aside.
In a small saucepan over low heat, mix together the brown sugar, molasses, butter, corn syrup, and salt, stirring until the butter is melted. Cook without stirring for 3 minutes.
Stir in the baking soda and vanilla extract, then immediately pour the pan's contents over the popcorn mixture. Stir until evenly coated, then spread the mixture on the prepared baking sheet.
Bake the mixture for 15 minutes; let cool for 20 minutes. Loosen from the pan with a spatula and break into pieces before filling the cones.