Directions

1. Bring a pan of water to the boil. Lower the orange in and cover with a lid, leaving a gap so that a little steam can still escape. Boil gently for 30 mins, then remove from the water and allow to cool slightly. Quarter the orange and remove any pips, then transfer to ablenderorfood processor, add the lemon juice and zest and blitz to a smooth puree.
2. Heat the oven to 180C/160C fan/ gas 4. Oil the sides of a 23cm round cake tin and line the bottom of the tin with baking parchment.
3. Sieve the almonds, polenta, baking powder and 1/2 tsp salt into a large bowl and mix together thoroughly.Whiskthe eggs and sugar in the bowl of a stand mixer until really pale and fluffy, about 4 mins. With the mixer still whisking, slowly pour in the olive oil in a steady stream so that the mixture doesn't split. Once incorporated, scrape in the orange puree and whisk to combine, then add the dry ingredients, combining until you have a smooth batter. Pour the batter into the cake tin and bake for 55 mins to 1 hr 5 mins until a skewer inserted into the middle comes out clean.
4. Cool in the tin on a wire rack while you make the syrup. Combine the sugar, orange juice, lemon juice, cardamom and 30ml water in a pan. Bring to the boil, stirring until the sugar has dissolved, then add the rosemary. Turn off the heat and infuse for at least 30 mins.
5. Use a skewer to poke holes in the top of the cake, then pour over the syrup. Allow to settle for 5 mins or so, then slice and serve with some natural yogurt or creme fraiche, if you like.