Preheat your oven to 160C/320F. Grease and line an 8" round cake tin with baking paper.
Place the oranges in a large pot with water. Bring the water to boil, and then turn down the heat to a simmer for 45 min or until the orange skin is soft and tender.
When the orange is cool to touch, quarter the oranges (remove any seeds) and place it in a food processor. Blend the oranges together until smooth.
In a large bowl, use an electric mixer to beat the eggs and sugar together until very pale and thick.
Add the orange mixture, almond flour, baking soda, cinnamon, and cardamom to the egg and sugar mixture. Gentle fold through the ingredients until well mixed together.
Carefully pour the mixture into the prepared cake tin. Smooth and level the surface.
Bake in the oven for 60 minutes, or until the toothpick inserted into the middle comes out clean. Allow the cake to cool whilst making the syrup.
To make the syrup, zest the orange and set aside.
Then juice the orange and add the juice to into a small saucepan together with water and sugar.
Over low heat, gently simmer the syrup until the sugars dissolve, stirring constantly using a whisk until the syrup thickens.
Add the orange zest and rose water to the saucepan.
Use a toothpick to prick holes on the cake and drizzle the syrup evenly around the cake.
Garnish cake with chopped pistachios and dried rose petals.