Line the base and sides of a 20cm sandwich tin with two layers of cling film.
In a small saucepan over a low heat melt together the syrup and chocolate, mixing until smooth.
Put the crunchy nut cornflakes into a large bowl and use your hands to scrunch them up so they are a bit smaller in size. Finely chop the peanuts (or use a food processor) and add to the large bowl.
Pour over the melted chocolate and mix really well to combine.
Use this sticky mix to evenly line the base and sides of the cake tin. Wet fingers will stop the mix from sticking and make it easier to spread.
Set aside in the fridge to chill.
Filling:
Finely chop the white chocolate and place in a large bowl.
Add the double cream to a saucepan and gently heat until it reaches boiling point, then pour over the bowl of chopped chocolate. Leave to sit for a few minutes, then stir it all together until the chocolate is completely melted.
Add the butter and mix until melted through then pour into the cereal-lined cake tin.
Chop some of the peanuts and leave some whole, then scatter over the tart along with the crunchy nut cornflakes.
Leave to set in the fridge for a couple of hours.
Remove from the tin by gently lifting and removing the clingfilm. Transfer to a serving plate and slice up.
