baked caramel popcorn

the goods:

10 cups plain popcorn, popped

1 cup brown sugar, packed

1/4 cup light corn syrup

1/2 cup (1 stick) unsalted butter

1/8 teaspoon cream of tartar

1/2 teaspoon salt

1/2 teaspoon baking soda

Preheat oven to 200 degrees. Spread the popcorn out onto a large, foil-lined and lightly greased rimmed baking sheet.
In a medium saucepan set over medium heat, combine the sugar, corn syrup, butter, cream of tartar, and salt. Bring to a simmer stirring constantly. Allow to simmer for 3 minutes. Remove from heat and quickly stir in the baking soda. Pour the caramel over the popcorn and stir gently until it is evenly distributed and coating the kernels. Bake for 1 hour, stirring every 20 minutes. Allow to cool on the baking sheet, then break apart any large clusters.