Preheat your oven to fan-assisted 160C / 180C / 350F /gas 4 lightly oil a lined 9-inch round cake tin.
Arrange the blood orange slices at the base of the lined tin in a single layer and set aside.
Combine the polenta, flour, cardamom, baking powder, sodium bicarbonate and salt in a large bowl and set aside.
In a separate bowl, whisk together milk, orange juice, olive oil and maple syrup.
Pour the wet ingredients into dry ingredients and mix until combined.
Pour the cake batter into the cake tin and bake for 30 – 35 minutes in the preheated oven, or until a skewer inserted into the centre of the cake comes out clean.
Remove the cake from the oven and let it cool for 5 mins, before inverting onto cooling rack to cool further.
Notes
Slightly adapted from the blood orange polenta cake by The Whinery.