Mix 12 cups unsalted popcorn and 15 chopped Do-si-dos with 1/2 cup each salted peanuts and peanut butter chips in a large bowl. Bring 1 cup light brown sugar and 1/4 cup corn syrup to a boil in a small saucepan over medium-high heat. Gradually stir in 1 sliced stick cold butter until melted. Off the heat, whisk in 1/2 teaspoon each baking powder and kosher salt. Pour over the popcorn mixture and stir to coat. Transfer to a parchment-lined baking sheet. Bake at 350˚, stirring halfway through, until crisp, 15 to 20 minutes. Sprinkle with salt and let cool.