Butter Toffee Popcorn

This is seriously the best Caramel popcorn that you'll ever try. Yes, it's time consuming to make, but it's sooooooooo worth the effort to make the popcorn from scratch. In fact, I know I'll be making this popcorn again when Christmas rolls around for our Christmas treat tins. 

Butter Toffee Popcorn(Source: Cooks Country)
3 quarts popped popcorn (about 2/3 cup unpopped popcorn)10 tablespoons (1 1/4 sticks) unsalted butter1 1/2 cups packed light brown sugar1/2 cup dark corn syrup1/2 teaspoon salt1 1/2 teaspoons vanilla extract1/2 teaspoon baking soda2 cups salted peanuts
Adjust oven rack to middle position and heat oven to 250 degrees. Grease large roasting pan. Place popcorn in pan.
Melt butter in large saucepan over medium-high heat. Add brown sugar, corn syrup, and salt and bring to boil. Reduce heat to medium-low and simmer, stirring occasionally, until slightly thickened, about 3 minutes. Off heat, stir in vanilla and baking soda (mixture will foam). Add peanuts and pour mixture over popcorn, tossing to coat.
Bake, stirring occasionally, until popcorn is deep golden brown and caramel has set, 1 to 1 1/2 hours. (I stir my popcorn mixture every 10 minutes so all the kernels are coated evenly with the toffee mixture.) Cool to room temperature. Serve. (Popcorn can be stored in airtight container at room temperature for 5 days.)