• Preheat oven to 325°F Fit a piece of parchment paper to the bottom of a 9-inch springform pan that has 3-inch sides. Spray the with cooking oil.

To Make the Brownie Base Layer:

• In a large saucepan set over low heat, add the chocolate and butter, stirring constantly until they are melted. Remove the saucepan from the heat and add the sugar, instant espresso powder and salt, stir until well combined. Let cool slightly, then gradually stir in the beaten eggs and the vanilla extract. Add the flour and stir until blended. Fold the cocoa nibs into the batter and pour into the prepared baking pan.
• Bake the brownies in the center of the oven for 30-32 minutes, it should still be a little jiggly in the center but will firm up as it cools. Transfer to a cooling rack. Once cool, loosen the edges with a sharp knife.

To Make the Paper Cake Collar:

• Measure around the pan and cut a piece of parchment paper the length, plus a couple inches to overlap. Fold the parchment paper to a double thickness that is 5-inches wide.
• Clean the pan ring and wipe it dry, spray the inside of the ring with cooking oil and place it on the serving plate, fitting it around the brownie layer with the paper collar between the pan side and the brownie, flush with the serving plate. Snap the ring latch closed. The brownie layer will serve as the bottom of the cake and you will not need the metal pan bottom. Set aside while preparing the amaretto mousse.

For the Amaretto Mousse Layer:

• Chop the chocolate into pieces and add to the top of a double boiler which is set over barely simmering water and allow to melt undisturbed.
• Meanwhile, in a large mixing bowl beat the egg yolks until they are thick and pale, beat in the amaretto. Add the melted chocolate by spoonfuls, beating until the mixture is combined well.
• *Optional: For a very smooth textured mousse, pass the chocolate mixture through a fine mesh sieve, scraping the outside of the sieve, then proceed with the egg whites and whipped cream.
• In another bowl beat the egg whites until they just hold soft peaks, beat in ¼ cup of the sugar a little at a time and continue to beat the meringue until it holds stiff peaks. Beat in the vanilla. Stir one-third of the meringue into the chocolate mixture and fold in the remaining meringue.
• In a chilled bowl beat 1-1/4 cups of the heavy cream until it holds soft peaks, beat in the remaining ¼ cup of sugar and beat the cream until it holds stiff peaks. Fold the whipped cream into the chocolate mixture, gently incorporating it completely.
• Pour the mousse into the prepared springform pan, directly on top of the brownie layer, smoothing the top. Drape a sheet of plastic wrap lightly over the cake and refrigerate until until firm. About 2 hours.

To Make the Espresso Mousse:

• Chop the chocolate into pieces and add to the top of a double boiler which is set over barely simmering water and allow to melt undisturbed.
• While the chocolate is melting, sprinkle the gelatin into 1/4 cup of cold water and set aside for 1 minute to bloom.
• In a small saucepan bring the 1/2 cup of water to a boil, remove the pan from the heat and add the espresso powder, stirring to dissolve. Add the softened gelatin, stir to combine with the espresso and set aside to cool.
• In a large mixing bowl beat the egg yolks until they are thick and pale, beat in the cooled espresso mixture. Add the melted chocolate by spoonfuls, beating until the mixture is combined well.
• Optional: For a very smooth textured mousse, pass the chocolate mixture through a fine mesh sieve, scraping the outside of the sieve, then proceed with the egg whites and whip cream.I
• n another bowl beat the egg whites until they just hold soft peaks, beat in ¼ cup of the sugar a little at a time and continue to beat the meringue until it holds stiff peaks. Beat in the vanilla. Stir one-third of the meringue into the chocolate mixture and fold in the remaining meringue.
• In a chilled bowl beat 1-1/4 cups of the heavy cream until it holds soft peaks, beat in the remaining ¼ cup of sugar and beat the cream until it holds stiff peaks. Fold the whipped cream into the chocolate mixture, gently incorporating it completely.
• Remove the pan with the brownie and the amaretto mousse layer from the refrigerator, discarding the plastic wrap drape.
• Pour the espresso mousse into the prepared pan on top of the firm amaretto mousse layer. There should still be about an inch of the collar extended. Smooth the top, drape a sheet of plastic wrap lightly over the cake, not touching the mousse, and refrigerate until set, then transfer to the freezer to firm up, at least 2 hours. The collar will remove more cleanly if the cake is very cold.
• Transfer the mousse cake from the freezer and release the metal ring. Carefully, peel the parchment paper collar from the side of the mousse. If the mousse seems to be sticking to the collar return it to the freezer for a little longer. You will not need to reposition the metal pan ring.
• Once the collar has been removed, garnish with chocolate curls and place the layered mousse cake into the refrigerator until serving time. Alternatively, the cake may be frozen for up to one week, remove from the freezer and refrigerate for 2 hours or more, to thaw completely. Garnish with chocolate curls and serve.T
• To slice the cake with clean cuts, dip the knife into hot water and wipe clean after each slice.