Break 3 ounces of the chocolate into pieces and place the pieces in a bowl set over a pan of simmering water. Whisk in the coffee liqueur, water and espresso granules and heat the mixture until the chocolate just melts. Remove from the heat and set aside to cool.
Place the egg yolks and sugar in the bowl of an electric mixer fitted with the paddle attachment and beat on medium speed for 3 minutes, until the mixture is the texture of mayonnaise. Add the cocoa powder and vanilla, and slowly pour in the cooled chocolate mixture.
Put the egg whites and salt in the clean bowl of an electric mixer fitted with the whisk attachment and beat on high speed until the whites form soft (not dry!) peaks. Fold them carefully into the chocolate mixture. In the same bowl (no need to clean it) beat the heavy cream until it forms soft peaks and fold it carefully into the chocolate mixture. Grate the remaining 4 ounces of chocolate and fold it into the mixture.
Pour the mixture into a 10-cup souffle dish, cover with plastic wrap and freeze for several hours or overnight.
For the whipped cream, place the heavy cream, sugar and vanilla in the bowl of an electric mixer fitted with the whisk attachment, and whip on medium and then high speed until it reach stiff peaks. Spoon the whipped cream into a pastry bag fitted with a large star tip. Pipe the edge of the mousse with the whipped cream, and sprinkle extra chocolate shavings over the center of the mousse for decoration. Serve frozen.
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