01 - Line an 8x8-inch baking pan with parchment paper, leaving enough overhang on the sides to lift the bars out easily after setting.
02 - In a large saucepan, melt 1/2 cup unsalted butter over low heat. Add the sweetened condensed milk and granulated sugar, stirring constantly until the sugar fully dissolves and the mixture is smooth.
03 - Remove the saucepan from heat. Stir in 1 cup semisweet chocolate chips, vanilla extract, and a pinch of salt. Continue stirring until the chocolate is completely melted and the mixture is glossy and uniform.
04 - Gently fold the cornflakes into the chocolate mixture using a spatula, taking care not to crush them. Ensure every flake is evenly coated.
05 - Transfer the coated cornflake mixture into the prepared baking pan. Press firmly and evenly using the back of a spatula or your hands to create a compact, level base layer.
06 - Combine the remaining 1 cup semisweet chocolate chips, heavy cream, and 2 tablespoons unsalted butter in a microwave-safe bowl. Microwave in 20-second intervals, stirring thoroughly between each burst, until the mixture is completely melted, glossy, and smooth.
07 - Pour the fudge topping over the cornflake base, spreading it into an even layer with a spatula. Ensure full coverage to the edges of the pan.
08 - Refrigerate the pan for at least 1 hour, or until the fudge topping is firm and set to the touch.
09 - Lift the slab out of the pan using the parchment overhang. Place on a cutting board and slice into 16 even bars. Serve chilled or at room temperature.