Preheat oven to 170°C / 340°F (150°C fan). Grease a 20 cm/8" springform pan with olive oil then line with baking paper (parchment paper), then grease the paper. (Note 6)

Dry ingredients: In a medium bowl, mix the hazelnut meal, baking soda, lemon and salt.

Beat wet ingredients: In a large bowl, beat the olive oil, eggs and sugar for 2 to 3 minutes on speed 7 of a handheld beater or until it becomes pale and thick (like pouring cream).

Add vanilla and beat on speed 1 for 10 seconds.

Mix in dry: Add the Dry ingredients and mix in gently using a rubber spatula.

Bake 45 minutes: Pour the batter into the prepared pan and bake for 45 minutes. It will puff up dramatically in the oven but it collapses as it cools.

Cool: Remove from the oven and allow the cake to fully cool in the pan before releasing from the springform pan. This is a rustic cake that has higher edges and a flatter centre. Perfect proportions, I say: plenty of meringue-like edges and not an overwhelming amount of the rich brownie-like centre of the cake!

Decorate: Sprinkle with hazelnuts and dust with icing sugar, if desired. Serve fully cool.