Step 1

Preheat the oven to 180°C (160°C fan-forced). Grease a deep 20cm square cake pan; line the base with baking paper.

Step 2

Process the pistachios until as finely ground as almond meal. Finely grate rind from oranges. Squeeze the juice from oranges – you will need 1 cup. Combine pistachio and almond meal, rind, sugar, cinnamon and salt in a large bowl with a balloon whisk.

Step 3

Beat the eggs, vanilla and butter in a medium bowl until combined. Pour the egg mixture into the almond mixture; whisk until well combined.

Step 4

Pour the mixture into the prepared pan. Bake for 55 minutes or until golden and coming away from the sides of the pan, and a skewer inserted into the centre comes out clean. If top starts to brown too much, place a piece of foil loosely over cake in the last 15 minutes of cooking.

Step 5

Meanwhile, stir orange juice, the water and extra sugar in a medium saucepan over medium heat, without boiling, until the sugar dissolves. Bring to the boil; boil, uncovered, without stirring, until reduced to about 1 cup. Skim any froth from the surface. Adjust the water content if syrup is too strong.

Step 6

When the cake comes out of the oven, carefully pierce the top with a skewer and pour the hot syrup over the hot cake. Leave the cake in the pan to allow the syrup to soak in.

Step 7

Serve cake warm or cooled with extra chopped pistachios, orange rind and thick yoghurt or double cream.