Place popped popcorn in a large bowl, set aside. Preheat oven to 250°F.
In a large nonstick pan on the medium heat, place butter, brown sugar, corn syrup, and salt. Bring mixture to a boil, then turn heat down to low and simmer for 3 minutes.
Remove the pan from the heat and mix in vanilla and baking soda. The caramel will foam up, but just continue to mix it until it's all gone.
Slowly drizzle caramel onto the popcorn as you mix it. It's definitely easier with two people if you have someone who can mix while you pour or vice versa. Once the popcorn is well coated, place on a couple of baking sheets with parchment paper and bake for 1 hour. You can attempt to mix it a couple times during that hour so the caramel doesn't sink to the bottom too much.
Allow the popcorn to cool completely, then drizzle melted chocolate on top of popcorn. You can dip several pieces in with toothpicks as well if you want to be more moose munch authentic. Let the chocolate set, then add in your favorite chocolate candies or eat as is.