Preheat the oven to 300°F (150°C). Generously grease 3 (8-1/4-inch) pie pans or molds; Cut 3 rounds of waxed paper to line the bottom of each mold and generously grease the waxed paper.
To prepare the meringue, in a large bowl, using an electric mixer on high speed, beat the egg whites with the salt and cream of tartar; Slowly add the sugar and continue beating until stiff peaks form; Divide the egg whites among the three molds and smooth the tops with a spatula; Place in the oven and immediately decrease the heat to 275°F (135°C); Bake until the meringue is hard but not brown, about 1 hour; (At this point, you can turn off the oven and let the meringues stand for a few hours or overnight).
To prepare the ganache, reserve 12 hazelnuts for garnish; In a food processor, grind the remaining nuts with 1 tablespoon of the sugar until you have a fine meal.
Combine the chocolate, coffee, brandy, and remaining 2 tablespoons sugar in a heatproof bowl; In a large, heavy skillet, bring water to a simmer over medium-high heat; Remove the skillet from the heat; Place the bowl filled with the chocolate mixture in the skillet and stir gently until the chocolate melts; Set aside and allow to cool slightly.
Pour the cream into a large chilled bowl and whip with an electric mixer on high speed until stiff peaks form; Gently fold the melted chocolate into the whipped cream, and then fold in half of the ground nuts.
To assemble the cake, carefully peel the paper from the bottom of each meringue; Set one round on a serving platter; With a spatula, spread one third of the ganache over the top; Cover with a second round, and repeat the procedure; Top with the third round, and spread with the remaining ganache, spreading it over and around the sides of the cake; Sprinkle with the remaining ground hazelnuts and garnish with the whole nuts; Refrigerate for 2 to 6 hours before serving.