Preheat your oven to 350°F (175°C).
In a mixing bowl, cream together the softened butter, brown sugar, and granulated sugar.
Add the egg and vanilla extract; mix until well combined.
In another bowl, sift together the flour, baking soda, and salt.
Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Gently fold in the cornflakes and chocolate chips.
Drop spoonfuls of the dough onto a baking sheet lined with parchment paper.
Bake in the preheated oven for 12-15 minutes, or until edges are golden.
Remove from the oven and let cool on the baking sheet for 5 minutes.
Transfer to a wire rack to cool completely.