Triple Layer Chocolate Mousse Cake - chocolate mousse

Method

• Make the chocolate mousse: Put the chocolate in a food processor fitted with the metal chopping blade.
• Process for 20 to 30 seconds, until finely ground.
• In a small saucepan, combine the milk, sugar and salt.
• Cook over medium heat, stirring with a wooden spoon, until the sugar dissolves and the milk comes to a boil.
• Remove the pan from the heat.
• With the motor of the food processor running, pour the hot milk through the feed tube.
• Process for 10 to 20 seconds, until the chocolate is completely melted.
• Using a spatula, scrape down the side of the work bowl.
• Add the oil and vanilla extract; process for 5 to 10 seconds, until the mixture is creamy.
• Scrape the chocolate mixture into a large bowl and cool for about 5 minutes, until tepid.
• In a chilled 4-1/2 quart bowl of a heavy-duty electric mixer fitted with the wire whisk attachment, whip the cream until soft mounds barely start to form and the cream is still pourable.
• Do not overwhip the cream.
• Using a large rubber spatula, gently fold one-third of the whipped cream into the tepid chocolate mixture to lighten it.
• Fold in the remaining whipped cream.
• Do not overfold the mousse or the texture will be grainy.
• Cover with plastic wrap and chill for 6 to 8 hours or overnight, until firm.
• Make the cake: Grease three 10-inch round cake pans.
• Cut three 10-inch circles of waxed paer and place in the bottom of each pan.
• Grease the pan well and then flour, tapping out the excess.
• Set aside.
• Place the oven racks two shelves apart.
• Preheat the over to 350 degrees F.
• Sift together the flour, baking soda and salt.
• Set aside.
• Place the coarsely chopped chocolate and the water on top of a double boiler and turn heat to medium-high, whisking occasionally until smooth.
• Remove from the top of the double boiler and cool slightly.
• Meanwhile, in a 4-1/2 quart bowl of a heavy-duty electric mixer using the paddle attachment, cream together the butter and the sugars.
• Add the vanilla.
• Add the eggs one by one, mixing on medium speed until blended.
• Using a rubber spatula, scrape down the sides of the bowl.
• With the mixer at its lowest speed, add half of the dry ingredients and the half of the buttermilk.
• When blended, add the remaining buttermilk and the chocolate mixture.
• Mix until blended then add the remaining dry ingredients.
• Mix on medium speed just until blended and the flour lumps disappear.
• Divide evenly among the three prepared pans and smooth the tops with an offset metal spatula.
• Bake for 28 to 32 minutes, or until a toothpick comes out clean.
• Remove the pans from the oven and place on wire cooling racks.
• Cool for 15 minutes and invert.
• Peel off the waxed paper and cool completely.
• Begin to assemble the cake: Place a dab of chocolate mousse and then a layer of the cooled cake on a 10-inch cardboard cake circle or the circular insert of a tart pan.
• Using a large rubber spatula, place about one-quarter of the chilled chocolate mousse on top of the first cake layer.
• Using a metal cake spatula, spread the mousse evenly not quite to the sides of the cake.
• There should be slightly less than one-half inch of mousse on top of the cake.
• Place the second cake layer on top and repeat the mousse layer.
• Place the third cake layer on top, then spread the remaining chocolate mousse over the top and sides of the cake, coating smoothly and evenly.
• Place the cake in the freezer for a minimum of four hours.
• Make the ganache glaze: Place the coarsely chopped chocolate in a food processor fitted with the metal chopping blade.
• Process for 20 to 30 seconds, until finely ground.
• Place in a large bowl.
• In a medium pan, scald the heavy cream and pour over the chocolate.
• Using a metal whisk, gently stir until smooth and melted.
• Continue stirring until the ganache is room temperature or just slightly warmer.
• Glaze and garnish the cake: Place the Oreos in a food processor fitted with the metal chopping blade.
• Process for 20 to 30 seconds, until finely ground.
• Remove the cake from the freezer and place on a wire rack that has been set over aluminum foil or a sheet pan.
• Slowly pour the ganache over the top of the cake, smoothing with a large metal cake spatula.
• When the top has been coated, slowly pour the ganache around the sides of the cake so it drips down and coats the sides.
• Use the spatula to spread the ganache evenly over the sides of the cake.
• When completely coated with the ganache, scoop the Oreo crumbs with your hand and press them onto the sides of the cake, coating its entirety.
• Refrigerate until ready to serve.