Put some baking paper on the work surface.

Put the marshmallows and butter in a heatproof bowl and put it on top of a pan of simmering water - the bottom of the bowl should not touch the water! Let it melt, but stir occasionally.

Put the cereal into a large bowl. Pour over the melted marshmallows and combine well with a wooden spatula.

Pour some oil into a little bowl. Put in your fingers and rub the oil into your hands. Tear off some of the mixture and create oval ‘brain’ shapes between your palms. Make them about 5-6 cm long. Put them on the baking paper and adjust their shape with your fingers .

When you've shaped all the brains, using a blunt knife, press down along the center of each brain to create a groove.

Dip a skewer into jam or red icing and draw squiggly lines all over the brains to represent ‘blood vessels’. Alternatively use a red gel writing pen.

Let them set for about 4 hours or until firm.