In a double broiler or in a microwave safe bowl (stirring and heating for 30 second intervals until mostly melted) melt the Bittersweet Chocolate chunks.
Transfer melted chocolate into large mixing bowl, stir in blended hazelnuts.
Add the olive oil, vanilla, orange zest, espresso powder, and sea salt. Stir until combined set aside.
In the bowl of a stand mixer fitted with whisk attachment on high, beat egg whites until soft peaks form.
Continuing to mix on medium high speed, slowly pour in sugar and continuing whipping until stiff peaks form.
Transfer stiff egg whites to the bowl of chocolate mixture. Fold egg whites completely into the chocolate mixture. You can use a hand whisk or a spatula, but make sure to completely incorporate the egg whites. No white streaks should be visible.
Now you can transfer chocolate mousse to glass goblets, cups, or serving bowls. Use a spoon or transfer mousse to a large piping bag and cut a large tip. Then gently pipe chocolate mousse into serving vessel.
Place in the fridge to chill for 1-2 hrs.