Preheat your oven to 160°C.

Mix the brown sugar and water together, and spread this over the base of a loose bottomed cake tin, lined with parchment. Arrange the orange slices over the sugar mixture, and set aside.

Add the egg whites to the bowl of your kitchen machine fitted with the balloon whisk and whisk on high speed until you have stiff peaks. Scrape the egg whites into a separate bowl, and reserve.

Into the bowl of the kitchen machine, add the yolks, sugar and orange zest and whisk on speed 4 for 3 minutes or until fluffy.

Add the vanilla, olive oil, ricotta and orange juice and mix on speed 1 until combined.

Add the flour, baking powder and salt and mix until combined.

Fold the egg whites into the rest of the mixture and then spoon into the cake tin, being careful not to move the orange slices.

Bake in the preheated oven for 30-40 minutes, or until a skewer inserted into the middle of the cake comes out clean.

Leave to cool then remove from the tin and invert onto a serving plate.