First of all, when the oven is pre-heated you need to roast all the pistachios (for the cake and the topping) – just spread them out on a tray and pop them into the oven near the centre for 8 minutes – use a timer to help you remember.
While that’s happening, place the 10 cardamom pods for the cake in a mortar, bash them about to split the pods open, then remove the seeds to a saucer. Now do the same with the 10 pods for the syrup, using a separate saucer.
Next discard all the pods and grind each lot of seeds, keeping them separate, to a fine powder. When the nuts are ready, chop half of them finely and keep the rest on one side for the topping.
Now to make the cake. First of all, sift the flour and baking powder into a roomy mixing bowl, lifting the sieve quite high to give the flour a good airing as it goes down. Then add the butter, eggs, caster sugar, instant espresso and one saucer of cardamom powder, and using an electric hand whisk, mix to a smooth, creamy consistency for about 1 minute.
After that fold the chopped nuts into the mixture with a tablespoon. Now divide the mixture between the two prepared tins, level off using the back of a tablespoon and bake near the centre of the oven for about 25 minutes.
Meanwhile you can make up the syrup and the topping.
Place the coffee powder, the other saucer of crushed cardamom and sugar in a heatproof bowl, then measure the boiling water into it and whisk for about one minute until the coffee and sugar have dissolved.
For the filling and topping, whisk all the ingredients except the pistachios together in another bowl. The cakes are cooked when you press lightly with your little finger and the centre springs back.
Remove them from the oven but leave them in their tins. Prick them all over with a skewer while they are still hot and sprinkle the syrup as evenly as possible over each one, leaving them to soak up the liquid as they cool in their tins.
When they are absolutely cold, loosen the edges with a palette knife, then place each one on an upturned bowl and carefully slide the outer edge of the tin downwards. Choose a serving plate and, using a palette knife, gently slide one cake off its liner onto the plate.
Then spread half the filling mixture over the first cake. Then (as above) slide the other cake carefully on top, and spread with the other half of the mixture.
To finish, scatter the roasted pistachios all over just before serving.
Store in a polythene box in the fridge until needed.