chocolate 'no bake' slice

Directions

1. 1
   lightly grease a 20cm square tin.
2. 2
   put 125g butter and the sugar in a medium pot.
3. 3
   stir over low heat until the butter has melted and the sugar has dissolved.
4. 4
   stir in the crushed biscuits,chopped nuts and cocoa, mix gently until well combined.
5. 5
   remove from heat and stir in the egg until combined.
6. 6
   press the mixture into prepared tin, smooth the surface.
7. 7
   refrigerate.
8. 8
   place the chopped chocolate and remaining butter in a heatproof bowl.
9. 9
   stand over a pan of simmering water.
10. 10
    stir until both have melted.
11. 11
    spread chocolate over the slice.
12. 12
    return to fridge for at least an hour.
13. 13
    cut into squares or bars before serving.