Carrot sponge

In a large mixing bowl combine the flour, cinnamon, ginger, turmeric, nutmeg, baking powder and orange zest; mix with a whisk and set aside.

In a stand mixer bowl put the eggs, sugar, scraped vanilla seeds and salt; whip on high speed several minutes until increased in volume, very thick, pale, almost white and fluffy.

With the mixer on medium, add the olive oil heated to 45C in a slow, steady stream so the mixture emulsifies like a mayonnaise and does not deflate much.

Fold in the dry ingredients gently with a whisk in two or three portions.

Switch to a spatula and fold in the grated carrots, then the chopped roasted walnuts, until smooth with no lumps of flour.

Divide the batter into three cake rings lined with aluminium foil on one side, around 550 g each.

Bake at 165C for around 30 to 35 minutes in a convection oven (160-165C); in a conventional oven add 5-10 minutes and 5-10C. Done when golden, the centre springs back and a toothpick comes out clean.

Cool at room temperature at least one hour (about two hours here) before unmolding.

Peel off the foil, run a sharp knife around the ring to release the sponge, and trim off the top crust with a serrated knife, rotating the sponge, so it is flat.

To keep: wrap in cling film in an airtight container, up to three days at room temperature (better with the crust left on until assembly), or frozen up to one month.