Prepare the Chocolate Cake Layers:

• Preheat the oven to 350°F (175°C). Grease and flour two 8-inch round cake pans.

• In a large bowl, sift together flour, sugar, cocoa powder, baking powder, baking soda, and salt.

• Add milk, eggs, sour cream, oil, espresso powder, and vanilla to the dry mixture. Mix until just combined.

• Stir in the hot water until the batter is smooth (it will be thin).

• Divide the batter evenly between the pans and bake for 30-35 minutes, or until a toothpick comes out clean.

• Cool the cakes in the pans for 10 minutes, then transfer to wire racks to cool completely.

Prepare the Dark and White Chocolate Mousses:

• Dark Chocolate Mousse: Melt dark chocolate over a double boiler or in the microwave. Let cool slightly.

• Whisk egg yolks and sugar until pale. Heat heavy cream until warm, then pour over the egg mixture, whisking constantly.

• Stir in the melted dark chocolate.

• Fold in whipped cream until soft peaks form.

• White Chocolate Mousse: Repeat the steps above using white chocolate in place of dark chocolate.

Assemble the Tuxedo Cake:

• Place one chocolate cake layer on a serving platter.

• Spread the dark chocolate mousse over the cake layer, then gently spread the white chocolate mousse over the dark mousse.

• Place the second cake layer on top.

• Refrigerate for at least 4 hours, or overnight, to set the mousses.

Apply the Chocolate Ganache:

• Heat heavy cream until scalding.

• Pour over chopped dark chocolate and let sit for 5 minutes. Stir until smooth.

• Let the ganache cool slightly before pouring over the chilled cake, allowing it to drip down the sides.

Decorate:

• Once the ganache sets, garnish with chocolate shavings or berries.