Preheat your oven to 180°C and line a baking tray with baking paper.
In a large bowl, cream the softened butter and sugar until light and fluffy.
Beat in the egg and vanilla essence.
Sift the flour, baking powder, and salt into the mixture and mix to form a soft dough.
Gently fold in the crushed cornflakes. You can keep some whole for extra crunch.
Roll tablespoons of dough into balls and place them on the tray. Flatten them slightly with your fingers or a fork.
Bake for 12 to 15 minutes or until the edges are golden brown.
Allow to cool on the tray for 5 minutes, then transfer to a wire rack to cool completely.