Preheat the oven to 180 degrees Celsius.
Cream butter and sugar until light and fluffy.
Add the egg and vanilla and beat well then stir in the cornflakes, raisins and flour and mix well.
Roll into balls then roll in the extra crushed cereal.
Place on baking tray and bake for 12 minutes.
Store in an airtight container for up to 2 weeks.