1. Place chocolate in a large heatproof bowl placed over a pot of simmering water. Melt chocolate, stirring frequently, for about 5 minutes or until smooth. Let cool slightly.
2. Whisk olive oil into melted chocolate; set aside. In a separate large bowl, beat egg whites with a pinch of sea salt until stiff peaks form. Set aside.
3. In a separate large bowl, beat egg yolks, remaining salt, and maple syrup until pale, thickened, and doubled in volume; gently fold in chocolate mixture.
4. In three additions, fold egg whites into chocolate mixture until smooth and no white streaks remain.
5. Spoon or pipe mixture evenly into 4 ramekins; refrigerate for 20 minutes. Garnish with a sprinkle of sea salt.

Tip: Mousse can be made ahead, covered, and refrigerated. Let stand at room temperature for 30 minutes before serving.