Position oven racks in the top and lower thirds of oven and heat oven to 325°F.
Outline four 8-inch circles on individual pieces of parchment paper and lightly coat with oil or butter.
Place hazelnuts, 1 cup sugar and salt in a food processor and blend until finely ground.
Using an electric mixer, beat egg whites until soft peaks form. Drizzle in vanilla extract, then slowly add remaining 2 tablespoons sugar. Beat until stiff but not dry.
Fold nut mixture into egg whites in ⅓ increments. Spread ¼ of macaroon batter evenly within each circle.
Bake macaroon layers until golden and dry to the touch, about 20 to 23 minutes. Cool on a cooling rack.
Make chocolate filling: Heat half of chocolate, water, and coffee in a saucepan over low heat, stirring until smooth. Off the heat, stir in second half of chocolate until melted.
Spread chocolate evenly over tops of meringue rounds and cool until chocolate is set.
Make whipped frosting: Beat cream with sugar and liqueur or vanilla until it holds stiff peaks.
Assemble torte: Peel parchment off macaroon rounds. Arrange first disc on serving plate, spread ⅓ cup whipped cream over it, and repeat with remaining rounds. Frost top and sides with whipped cream.
Decorate with chocolate shavings if desired. Serve immediately or store in fridge.
