Cornflake crunch:

1. Crush the cornflakes slightly.
2. Mix the dry ingredients in a bowl. Drizzle in the melted butter and mix well.
3. Spread the mixture in a baking tray lined with parchment paper and bake in the preheated oven at 350F for 15-20 minutes or until fragrant, slightly golden brown and crunchy. Allow to cool completely.

Cornflake cookies:

1. Combine the butter and sugars in a bowl and mix with an electric mixer for 2 minutes until pale and creamy.
2. Add the egg and vanilla and mix well for 7-8 minutes on high speed until fluffy and pale.
3. Add the flour, baking powder, baking soda and salt and mix just until combined then, using a spatula, fold in the cornflake crunch, chocolate chips and marshmallows.
4. Using an ice cream scoop, drop spoonfuls of batter on a baking tray lined with baking paper. Allow enough space between the cookies as they will spread quite a lot. Wrap the baking pan in plastic wrap and place in the freezer for 1 hour, up to 1 week.
5. Remove from the freezer when ready and bake in the preheated oven at 350F for 10-15 minutes or until they’re thin, golden brown on the edges and center and the edges are crisp.
6. Allow them to cool in the pan before serving. While hot, they are soft and might not hold their shape, but once cooled, they can easily be handled.
7. Store them in an airtight container for up to 5 days or freeze them for up to 1 month.