The secret to this delicious Hedgehog is not to break up the biscuits too small.
About 1cm pieces seem to work best.

1 packet Marie Biscuits
100g Margarine
100g Caster Sugar
2 Eggs
2 tbs Cocoa
melted Chocolate for topping

Break up Marie biscuits (not too small).
Melt margarine and caster sugar slowlyuntil sugar dissolves.
Remove from heat.
Beat eggs into cocoa with a whisk then add to sugar and margarine while still whisking.
Mix with Marie biscuits and pour into square tray.
Press up one end, about 2.5cm high.
Melt chocolate and pour on top.
Refrigerate overnight and then cut into 2 cm squares.