You will need a 28 x 20cm baking tray lined with greaseproof paper.
I wanted to put a cake on the dessert menu and so, after playing around with different ideas and ingredients, I came up with this stunning, pale-jade winner. I like to serve it with a jug of cold custard on the side, or a scoop of Apple Sorbet.
Preheat the oven to 160°C/325°F/gas mark 3.
Put the ground almonds and the pistachio nuts into a blender or food-processor and chop or grind them until very finely ground. Set aside.
In a large, clean bowl, cream together the butter and caster sugar until pale, light and fluffy. Add the pistachio paste and the finely ground nuts, mixing them in gently until smooth. Add the eggs one by one, beating well after each addition, then pour the batter into the lined baking tray. Use a spoon or spatula to smooth out the batter evenly.
Bake for 30 minutes, or until golden brown and firm to the touch. The cake should spring back when you press it gently with your finger. Then remove the cake from the oven and allow it to cool in the tray.
When the cake is cool, cut it into square tiles, and serve dusted with icing sugar. The cake will stay moist for 2-3 days because of the oil from the nuts.
You can buy pistachio paste in specialist baking stores, but if you cannot find it, substitute an extra 20g of ground pistachio nuts.