1. Preheat oven to 190°C and gently rub olive oil into a small cake tin. (I used a non-stick loaf tin with olive oil. You could also line your favourite tin with parchment paper.)
2. Melt the chocolate and olive oil over a bain-marie, being careful not to disturb it by mixing. Beat the egg yolks and sugar until pale and thick.
3. Beat the egg whites to a soft meringue with a pinch of salt. Gently mix the egg yolk mixture into the chocolate and olive oil, being careful not to overwork.
4. Fold in the egg whites until fully incorporated. Pour into the tin and bake for 10–12 minutes. The top of the cake should be set but not cracked.
5. Cool for at least two hours before serving. You can leave it on a wire rack or in the oven with the door open.
6. Cut a slice with a hot knife and serve with a sprinkle of sea salt.
7. The cake is excellent with a dollop of raw cream (lightly whisked) or crème fraîche. You could also use yoghurt if you prefer more acidity with your gâteau.