Not actually "traditional" fudge, but still quite tasty. This is my grandmother's recipe, with some modern touches.

1/2 lb butter
1 cup sugar
2 eggs
1 tsp vanilla essence
2 tbsp cocoa
2 packets crushed biscuits1 (milk arrowroots, marie, etc.)
Dried fruit (sultanas, mixed peel, etc.)

Process the biscuits in a food processor until thoroughly broken up2 (alternatively, put them in a bag and go smashy-smashy on them with a rolling pin). Melt the butter in the microwave until soft and mix with the sugar. Beat the eggs, cocoa and essence, then add to the butter/sugar mix. Stir in the crushed biscuits and add the dried fruit3. Smooth into a tin and refrigerate until firm. Ice with chocolate icing when cold.

It'll last for about a week and a half in the fridge, if you can somehow refrain from eating it all in that time.

1 "Sugar cookies", if you're an American. Thanks, enth.
2 Don't make them too fine - you're not aiming to make biscuit dust.
3 You'll need a lot more dried fruit than you think you will. Yes, more than that. Stop eating the orange peel.