Preheat the oven to 325 degrees Fahrenheit and line a medium-sized baking sheet with parchment paper.
Add the cornflakes to a large mixing bowl and set aside.
In a medium sized saucepan add the butter and brown sugar over medium heat. Stirring frequently, cook for about 6-8 minutes or until completely combined, the sugar has dissolved, and the mixture is bubbling. Remove from the heat and stir in the vanilla extract.
Immediately pour the mixture over the cornflakes and toss to combine, making sure all of the cornflakes are coated.
Pour the mixture onto the lined baking sheet and spread evenly, making sure the cornflakes aren’t too far apart from each other. Bake for 12 minutes, then remove from the oven.
Evenly sprinkle the chocolate chips over the top then place back into the oven for 2 minutes.
Using a silicone spatula, carefully spread the melted chocolate over the top until all of the cornflakes are covered.
Sprinkle the top with the flaky salt. Let the pan cool completely at room temperature, then place into the freezer for the chocolate to set completely, about 20 minutes. Break into pieces and enjoy!