Butter a 13- by 9-inch baking dish. In a pot over medium heat, melt the 3 tablespoons butter, then add the marshmallows and 1/2 teaspoon salt and melt, stirring frequently until smooth and combined.

In a large bowl, combine the popcorn and peanuts. Pour the melted marshmallow mix over the popcorn/peanut combination and mix until the popcorn is evenly coated and the peanuts are well distributed.

When the mixture is cool enough to handle, use a buttered spatula or clean, buttered hands to evenly spread and firmly press the popcorn mixture into the prepared baking dish. Sprinkle with salt. Let cool completely in the pan, 25 minutes.

Cut into 12 bars. In a microwave-safe bowl, heat the chocolate chips in the microwave (stopping periodically to stir), until melted. With a spoon, drizzle the chocolate over the bars. Let cool and harden, then enjoy.