1.
In a bowl over simmering water, melt the Mars Bars. When fairly soft, stir in the melted butter.
2.
Butter a deep 23cm cake tin and coat with the crushed biscuits. Combine the remaining crushed biscuits with finely chopped Twix bars.
3.
Stir the eggs into the melted Mars bar mixture. Remove from heat and stir in biscuit/Twix mixture, raisins and hazelnuts, until well mixed.
4.
Pour into prepared dish. Chill 8 hours or overnight in refrigerator. Turn out onto a serving plate and cut to serve. Keep chilled.