Wash the oranges, then place them in a small saucepan and cover with water. Bring to a boil, reduce the heat, and simmer for 1 hour. Remove from the water and set aside to cool slightly.

Once cooled, cut the oranges in half and remove the pips. Transfer to a food processor or blender, add the Grand Marnier, and blend for about 10 seconds until smooth.

In a large bowl, whisk the eggs and sugar until the sugar dissolves and the mixture becomes pale.

Gently fold in the orange and Grand Marnier purée, polenta, almond meal, and baking powder.

Line the base of a 25 cm – 10 inch springform cake tin with baking paper, then pour in the batter.

Bake in a preheated oven at 180 °C – 355 °F for 35–40 minutes. Leave to cool in the tin and set aside.

Place the sugar and 2 tablespoons of water in a small saucepan. Heat gently until the sugar melts and turns golden.

Add the orange juice and Grand Marnier. Bring to a boil, then add the cinnamon stick. Simmer for about 15 minutes, or until reduced by half.

Remove the cooled cake from the tin and place it on a serving plate.

Using a wooden or metal skewer, pierce holes over the top, then pour half of the syrup into the holes. Serve the remaining syrup alongside the cake.