These gooey bar cookies are perfectly sweet and savory.
Heat oven to 350 degrees. Brush two 9-by-13-by-2-inch baking pans with oil, line with parchment, and oil parchment. Set aside.
Heat oil in a large, heavy-bottomed stockpot over medium heat. When hot, add popping corn. Cover, and let cook until corn starts to pop. When the popping noises become infrequent, remove stockpot from heat.
Transfer popped corn to a large mixing bowl. Using a microwave or double boiler, heat caramel until liquid. Add caramel and peanuts to popcorn; stir with a wooden spoon until all popcorn is coated. Transfer mixture to one of the prepared pans, and, using the back of the spoon, pack mixture as tightly as possible.
Bake until caramel darkens, about 20 minutes. Transfer pan to a wire rack to cool for 5 minutes. Using hot pads, place other prepared pan on top, parchment side down. Invert popcorn into second pan, and transfer to a wire rack to cool. When completely cool and hard, cut into about 36 1 1/2-by-2-inch pieces.