01 - Line an 8x8-inch baking pan with parchment paper, leaving overhang on two sides for easy removal.
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. Add 1 cup semisweet chocolate chips, vanilla extract, and a pinch of salt. Stir 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, coating every flake evenly without crushing them to preserve the crunchy texture.
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 1 cup semisweet chocolate chips, 1/4 cup 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 fully melted and silky smooth.
07 - Pour the fudge topping over the cornflake base, spreading it into an even layer with a spatula. Ensure complete coverage from edge to edge.
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 slice into 16 even bars using a sharp knife. Serve chilled or at room temperature.