Preheat the oven to 190°C/170℃ fan/375°F/gas mark 5. Grease a deep, 23 cm/9 inch round cake tin with a removable base and line the bottom with baking parchment.
Whisk together the melted butter, sugar, milk, yogurt, orange zest and juice and rose water in a large bowl.
Place the cardamom pods in a mortar and bash with a pestle until the seeds come away from the pods. Discard the pods and grind the seeds to a fine powder.
Sift together the ground cardamom, nutmeg, almonds, flour, baking powder, bicarbonate of soda and salt.
Add the dry ingredient mixture to the wet annd stir with a balloon whisk until no dry lumps remain. Fold in the chopped pistachios.
Scrape the batter into the prepared tin and level the surface. Bake for about 35 minutes until a skewer inserted into the center comes out clean.
When the cake has nearly finished baking make the syrup. Place the caster sugar and lemon juice in a small pan over a low heat and stir until the sugar has dissolved, bring up to the boil then remove from the heat.
Leave the cake to cool in the tin for 10 minutes then poke holes in the top of the cake with a toothpick. Drizzle the syrup all over the top of the cake making sure that it soaks all of it up. Leave to cool in the tin for about 30 minutes then carefully turn the cake out onto a wire rack and leave to cool completely.
To make the icing, sift the icing sugar into a bowl and gradually stir in the lemon juice until it reaches a thick but pour-able consistency. Spoon the icing all over the top of the cake and gently coax it towards the edges with the back of a spoon.
Sprinkle the cake with chopped pistachios and edible dried rose petals and serve.