This is one of those desserts that looks complicated, but is super easy. From start to finish, it takes about a half hour of work, plus an hour of refrigerator time. My only caveat is that it contains raw eggs. It’s really no biggie so long as your eggs are fresh. But you might not want to feed it to the very young, the very old, or the immunocompromised.
4 oz. hazelnuts, plus a few for garnish
2 tbsp. frangelico
2 tbsp. butter
3 eggs, separated
1/2 cup cream + 1/4 cup to whip for garnish.
2/3 cup sugar
Toast your hazelnuts, then while they are still warm, place the 4 oz. that will go into the mousse into a towel, and rub them lightly but vigorously to remove some of the skins. You don’t need to be very thorough with this. In fact, a few skins add some attractive speckling to the finished product.
Place your rubbed hazelnuts into a food processor and chop them until they are fine and powdery (about 20 seconds). Add your egg yolks, butter, frangelico, and about 1/3 of the sugar, and pulse until you have a paste. Set aside.
Beat your egg whites until they form stiff peaks, but are not dry. About half way through, when they start to show some volume, add another third of the sugar. You don’t want to add it too early, because it will deflate the whites. But it is important because it gives your whites a nice shine that will transfer over to the final product.
Beat your 1/2 cup of cream with the rest of the sugar until it forms soft peaks.
Move you hazelnut mixture into a medium sized mixing bowl. Add about a tablespoon of the egg whites and with a spatula, beat vigorously to lighten the mixture up. Then, in thirds, add the rest of the egg whites, gently folding in each third with the spatula until the egg whites are integrated and the mousse is fluffy. Finally, add your whipped cream and continue to fold until the whole thing is homogeneous.
Ladle the mixture into 5-6 ramekins, and refrigerate immediately.
Meanwhile, beat the last 1/4 cup of cream, without any sugar, until it forms still peaks — almost, but not quite, until it is the consistency of butter. Remove your ramekins of mousse from the refrigerator, and top each one with a single spoonful of the unsweetened cream, plus three or four whole toasted hazelnuts.
Refrigerate again, and chill thoroughly before serving.