Begin by washing the oranges. Place one orange in a small saucepan, cover it with water, and bring it to a boil. Reduce the heat and simmer for approximately one hour, or until very soft. Remove the orange from the water and allow it to cool. Cut it in half and remove any pips. Chop it very finely—it will be quite mushy. Scoop it up and place it into a bowl.

Now, cut the remaining oranges into 3–5 mm thin slices. A sharp knife is key here!

Place the orange slices in a shallow pan, add enough water to just cover them, then add a tablespoon of golden caster sugar. Bring to a boil, then reduce the heat to a simmer and cook for 10 minutes. Remove the orange slices from the liquid and place them on a plate to cool. Once cool, arrange them so they overlap at the base of the tin.

Preheat the oven to 160°C (fan). Grease the sides of a 20 cm cake tin (not springform), then cut a disc of baking parchment to line the bottom.

For the orange syrup: Juice the remaining orange and add the juice, along with the sugar, to a small saucepan. Heat until it begins to bubble, then simmer over medium heat for 1 minute. Remove from the heat and set aside.

In a separate bowl, combine the polenta, baking powder, cardamom or ginger, and ground almonds. Set aside. In the bowl of a free-standing mixer fitted with a wire whisk attachment, beat the eggs with the sugar until very thick, light, and fluffy - this will take about 8 minutes. Gently fold in the dry ingredients, followed by the melted butter and the orange pulp.

Pour the batter over the arranged orange slices in the cake tin and place it in the oven immediately. Bake for 40 minutes, or until the cake is firm in the center and a skewer inserted into the middle comes out clean. Remove from the oven and allow it to cool on a wire rack for 15 minutes.

Transfer the cake to a plate and drizzle the orange syrup over the orange slices. Serve with Greek yogurt or crème fraîche.