Line a 20 x 30cm tin with baking
parchment. Melt the chocolate, butter
and golden syrup in a bowl set over a pan
of simmering water, stirring occasionally,
until smooth and glossy. Add the vanilla,
biscuits, sultanas and Rice Krispies,
and mix well until everything is coated.
Tip the mixture into the tin, then flatten
it down with the back of a spoon. Press
in some mini eggs, if using, and put in
the fridge until set. When hard, drizzle
all over with the melted white chocolate
and set again before cutting into chunks.