A Rich and fluffy four layer chocolate cake with chocolate mousse and white chocolate frosting.
Preheat oven to 375°F. Grease two 8-9 inch cake pans.
Place the flour, cocoa, baking powder and salt. Whisk until well blended.
Place the eggs in the bowl of an electric mixer. Whisk on high until very pale, (about 2 minutes). Slowly add the sugar and continue whisking at high speed until soft peaks form, another minute. Add the flour/cocoa mixture to the whipped eggs. Fold in carefully. Add the melted butter and fold in carefully.
Divide the batter equally into the prepared pans.
Bake for 20-25 minutes or until a tester inserted in the center comes out clean.
Remove from oven and let cool completely.
To make the milk chocolate mousse: Place the chocolate pieces in a double boiler. Melt the chocolate over simmering water, stirring constantly until smooth. Remove from heat and let cool until just warm to the touch. Place the heavy cream, chocolate liqueur and vanilla in the bowl of an electric mixer. Whip at medium speed until thick, Pour the melted milk chocolate into the whipped cream and fold until well blended, cover and refrigerate for 2 to 4 hours.
To make the white chocolate frosting, Place the white chocolate pieces in a double boiler. Melt the chocolate over simmering water, stirring constantly until smooth. Remove from heat and let cool until just warm to the touch. Place the heavy cream in the bowl of an electric mixer. Whip at medium speed until thick. Pour the melted white chocolate into the whipped cream and fold until well blended, cover and refrigerate for 2 to 4 hours.
To assemble the cake: Un-mold the chocolate cakes and cut in 4 layers. Place one layer of cake in the center of a serving platter. Using a pastry brush, soak the cake with one quarter of the coffee. Top with 1/3 of the white chocolate frosting and spread it evenly over the surface of the cake. Top with another layer of cake and all of the chocolate mouse, spreading evenly. Repeat soaking with the coffee and 1/3 white chocolate layer. Top with final layer of cake and finish by applying the white chocolate frosting.
Refrigerate for 4 to 6 hours. Remove from refrigerator 30 minutes before serving.