Caramel Popcorn and Peanut Clusters

• 12 cups plain popcorn (6 ounces)
• 1 cup roasted salted (cocktail) peanuts (6 ounces)
• 2 sticks (1 cup) unsalted butter
• 1 (1 pound) box light brown sugar (about 2 1/2 cups)
• 1/2 cup light corn syrup
• 1/2 teaspoon baking soda

Directions

Put popcorn in a large oiled roasting pan and top with peanuts.

Melt butter in a 3-quart heavy saucepan over medium heat. Add sugar and corn syrup and bring to a boil (still over medium heat), without stirring, with a deep-fat thermometer hooked to side, until the thermometer registers 250F, 5 to 8 minutes.

Immediately turn off heat and add soda, stirring until mixture lightens in color and changes texture, about 30 seconds. Pour mixture evenly over popcorn, quickly stirring with two wooden spoons to coat popcorn as much as possible. Spread caramel popcorn evenly in pan and let cool until caramel is hardened, about 30 minutes. Break into dessert size clusters pressing together as necessary.

Make ahead: Clusters keep in large plastic bags 3 days.