Cornflake Marshmallow Treats

Preheat oven to 325ºF (160ºC). Line two rimmed baking sheets with parchment and divide cereal evenly between the two sheets. Using your hands, gently crumble the cornflakes to break them up into smaller pieces. (They should not be as small as breadcrumbs; aim for the size slightly larger than that of Rice Krispies.) Toast in the oven, using a spatula to stir the grains occasionally, until deep golden brown, about 10 minutes. Remove from oven and cool for 5 minutes. When cool, lift both sides of the parchment to form a “sleeve” and transfer corn flakes to a large bowl. Set aside. Serious Eats / Amanda Suarez While the corn flakes toast, line a 9- by 9-inch baking dish with parchment and coat evenly with nonstick baking spray. Set aside. In a large pot, melt 4 tablespoons unsalted butter over medium heat, stirring and swirling, until solids turn golden brown and the butter smells nutty, 3 to 4 minutes. Reduce heat to low. Add salt, followed by marshmallows. Using a rubber spatula, stir until the marshmallows have just melted, about 4 minutes. Stir in toasted corn flakes, folding well to incorporate. Serious Eats / Amanda Suarez Transfer to prepared baking dish, using a rubber spatula greased with nonstick baking spray to coax the mixture into the pan. Garnish with flaky salt. Allow bars to cool for 30 minutes before portioning. Serious Eats / Amanda Suarez To portion, remove bars from the baking dish and place on a cutting board. Use a serrated knife to cut bars into squares, rectangles, or your desired shape. Serious Eats / Amanda Suarez