1. Preheat the oven to 350°C (175°C). Line a 9 inches (22cm) springform tin with baking parchment. Place the blueberries (if you use frozen ones let them defrost first) evenly distributed on the bottom of the tin and set aside.

 

2. In a large bowl mix the cane sugar with the eggs, and orange zest until light and fluffy. Add the passionfruit juice and oil and mix until well combined. In a second bowl mix the flour, polenta, baking powder, and salt. Add to the large bowl and mix until just combined. Pour over the blueberries and shake several times so big air bubbles can come out. Bake for 45-55 Minutes or until a skewer inserted into the center comes out clean. The cake should have a nice golden color on top. Take out of the oven and let cool down in the tin for 5 minutes. Loosen the cake from the sides, place a serving plate on top and turn upside down. Carefully remove the tin and baking parchment sticking to the blueberries and let cool down completely.