Stir together first 3 ingredients in a heavy saucepan over low heat, stirring constantly. Until chocolate melts, and mixture is smooth. Remove from the heat and cool slightly (about 10 minutes.) Whisk together eggs and vanilla. Gradually whisk in melted chocolate mixture until blended and smooth. Pour the batter into 3 greased 9" cake pans. Bake at 350 degrees for 25 - 30 minutes. Cool in pans on racks for 10 minutes. Remove from pans, and let cool completely. Spread 1/2 cup + 2 Tbs. Truffle filling evenly on top of 1 cake layer. Top with 1 cake layer, spread 1/2 cup + 2 Tbs. Truffle filling evenly on top, reserving remaining 1/2 cup Truffle filling. Top with remaining cake layer. Microwave coarsely chopped chocolate squares and cream 1 1/2 to 2 minutes, stirring after 1 minute; and then every 30 seconds until chocolate melts and mixture is smooth and slightly thickened. Let cool slightly (about 15 minutes). Spread warm chcolate mixture over the top and sides of cake. Chill cake 30 minutes or until chocolate glaze is firm. Pipe border using a rosette tip around bottom of cake with remaining 1/2 cup of Truffle filling. Sprinkle finely grated chcolate evenly over top of cake.