Step 1

Preheat the oven to 200ºC, gas mark 6. Blitz the cookies in a food processor, or put into a food bag, seal and bash with a rolling pin until fine crumbs form. Melt the butter in a saucepan or microwave, pour into the crumbs and stir until coated.

Step 2

Press the crumbs into a 20cm pie dish using your hands, pushing the mixture about 5cm up the sides of the tin. Use the back of a spoon to ensure the base is firmly pressed into the tin, then refrigerate until needed.

Step 3

For the fudge cake filling, whisk together the sugar with the eggs using a handheld electric whisk for 3-5 minutes, until thick and pale. Melt together the golden syrup, chocolate and butter in a bowl over a saucepan of just simmering water. Fold the chocolate mixture into the whipped eggs and sugar until well combined, then pour into the chilled base. Bake for 25-30 minutes, until a crust has formed but the centre retains a slight wobble, then allow to cool completely before returning to the fridge.

Step 4

While the cake bakes, make the topping. Melt the 80g chocolate in a heatproof bowl, stir in the custard and mix well. Set aside to cool.

Step 5

Whip the cream into soft peaks. Spread the chocolate custard mixture onto the top of the fudge cake, then spoon the cream over the top of that. Sprinkle over some chocolate shavings (see tip), then return to the fridge until ready to serve. This will keep, covered, for up to 3 days in the fridge.