For the Chocolate Cake Layers:

• 1 cup all-purpose flour
• 1 cup granulated sugar
• 1/3 cup unsweetened cocoa powder
• 1 teaspoon baking powder
• 1/2 teaspoon baking soda
• 1/4 teaspoon salt
• 1/2 cup buttermilk
• 1/3 cup vegetable oil
• 1 large egg
• 1/2 teaspoon vanilla extract
• 1/2 cup hot water

For the Dark Chocolate Mousse:

• 1 cup heavy cream (divided)
• 6 oz dark chocolate (chopped)
• 1/2 teaspoon vanilla extract

For the Milk Chocolate Mousse:

• 1 cup heavy cream (divided)
• 6 oz milk chocolate (chopped)
• 1/2 teaspoon vanilla extract

For the White Chocolate Mousse:

• 1 cup heavy cream (divided)
• 6 oz white chocolate (chopped)
• 1/2 teaspoon vanilla extract

For the Ganache Topping:

• 1/2 cup heavy cream
• 4 oz semi-sweet chocolate (chopped)