1. Preheat the oven to 160˚C, gas mark 3. Start by preparing the pistachios for both the marzipan and the cake. Place all 100g pistachios in a small bowl, pour boiling water over them, then drain. Rinse under cold water, then tip into a clean tea towel and rub to remove the skins; leave to dry for 15 minutes. Tip into a roasting tin and lightly roast for 15 minutes. Allow to cool, then blitz in the small bowl of a food processor until ground; set aside 50g for the marzipan and 50g for the cake.
2. For the marzipan, put the ground pistachios, almonds and sugars in a bowl. Add the almond extract, lemon juice and enough egg to bind (add a little at a time, you may not need it all). Knead gently; if it’s too sticky, add more ground almonds. Taste and add more almond extract if needed. Roll out one-third on an icing sugar-dusted surface, and using a 20cm round cake tin as a guide, cut out a circle; cover it with clingfilm. Wrap the remaining marzipan in clingfilm; set aside.
3. Grease a deep 20cm cake tin and line the base with baking parchment. Fold a strip of parchment around the outside of the tin and tie with kitchen string. For the cake, sift the flour, baking powder and spices into a bowl and stir in the ground pistachios. In a separate bowl, mix the dried fruit, cherries and mixed peel; set aside. Using an electric mixer or beaters, cream together the butter, sugar and citrus zests until light and fluffy. Beat in the eggs a little at a time, adding 1 tbsp of the flour mixture halfway through, until all the eggs are incorporated. Beat in the orange blossom water, then fold in the flour mixture, alternating with the dried fruit mixture.
4. Spread half the cake mixture into the prepared tin and put the marzipan circle on top. Spoon over the remaining cake mixture, smooth the top and put in the oven. Bake for 1 hour 45 minutes – 2 hours, until well risen and a deep brown colour. (If necessary, lay a piece of foil with a hole over the top to prevent it becoming too dark.) It is a little tricky to use the skewer test here, as the moist marzipan in the centre will always stick to the skewer.
5. Leave the cake in the tin for at least 15 minutes, then turn onto a wire rack to cool completely. To decorate, roll out two-thirds of the remaining marzipan on an icing sugar-dusted work surface to a 20cm circle to cover the cake. Warm the apricot jam with the orange blossom water gently in a small pan, then sieve. Turn the cake over (so it is base-side up) and brush the top with the jam. Lay the marzipan circle on top, and make a criss-cross pattern on the surface with a knife. Roll 11 balls from the remaining marzipan, and stick them to the cake with the jam.
6. Preheat the grill to high. Glaze the surface and balls with the egg yolk, and place under the grill. Watch carefully and grill until lightly toasted. Allow to cool before serving.