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 well combined.
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 into an even layer using the back of a spatula or your hands.
06 - In a microwave-safe bowl, combine 1 cup semisweet chocolate chips, 1/4 cup heavy cream, and 2 tablespoons unsalted butter. Microwave in 20-second increments, stirring thoroughly between each interval, 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 the entire surface is covered.
08 - Refrigerate the pan for at least 1 hour, or until the fudge topping is firm to the touch and fully set.
09 - Lift the slab out of the pan using the parchment overhang. Place on a cutting board and cut into 16 even bars. Serve chilled or at room temperature.