Preheat the oven to 250°F (120°C). Line a large baking sheet with parchment paper or a silicone baking mat.
Pop the popcorn and remove any un-popped kernels.
12 cups popped popcorn
In a large mixing bowl, combine the popped popcorn, peanuts, and chopped Snickers pieces. Set aside.
1 cup peanuts, 1 cup Snickers candy bars
In a medium saucepan over medium heat, melt the butter. Stir in the brown sugar, corn syrup, and salt. Bring the mixture to a boil, stirring constantly. Allow it to boil for 4-5 minutes without stirring. Remove the saucepan from heat and stir in the baking soda and vanilla extract. Be cautious as the mixture will bubble up.
1 cup unsalted butter, 1 cup brown sugar, 1/2 cup light corn syrup, 1/2 teaspoon salt, 1/4 teaspoon baking soda, 1 teaspoon pure vanilla extract
Pour the caramel sauce over the popcorn mixture and gently stir to coat evenly.
Spread the popcorn mixture onto the prepared baking sheet, spreading it out into an even layer. Bake in the preheated oven for 45-60 minutes, stirring every 15 minutes to ensure even coating.
Once the popcorn is done baking, remove it from the oven and immediately scatter the chopped candy bars over the top. Let it cool.
2 Snickers candy bars
In a microwave-safe bowl, melt the chocolate chips in 30-second intervals, stirring between each interval until smooth. Drizzle the melted chocolate over the top of the popcorn.
1 cup milk chocolate chips
Allow the chocolate to set for about 30 minutes or until firm.