Makes 25 squares.
Put the chopped fruit into a small pan along with the juice or alcohol and heat very gently until the fruit becomes plump and squishy, and has absorbed most of the liquid. Set aside to cool.
Break the biscuits into small pieces.
Line a roughly 20cm square brownie tin with baking paper (you can use a little butter to stick it down at the corners).
Break the chocolate into pieces by whacking the sealed packets against the kitchen counter. Put a heatproof bowl above, but not touching, a pan of water and bring to the boil. Tip the chocolate into the bowl, turn down the heat, and stir until the chocolate has melted. Take off the heat and allow to cool slightly.
Meanwhile, put the butter in a large mixing bowl with the syrup and use a wooden spoon, or electric beater, to beat them together until they're soft and a bit fluffy. Add the egg and mix in well.
Beat the chocolate into the butter mixture, then tip in the rest of the ingredients and stir until they're all coated with chocolate.
Spoon the mixture into your baking tin and press down firmly with a wooden spoon to make it as flat as possible.
Put in the fridge for a few hours until it has set solid, then lift the paper out, and cut into squares with a sharp knife.
Store in an airtight container in the fridge.
NovEmber 2013 in Perth
Felicity Cloake's perfect fridge cake. Photograph: Felicity Cloake for the Guardian