Good-Cooking - Bailey's Frozen Chocolate Chunk Mousse Cake

Ingredients

• 1/4 cup ground espresso
• 1/2 cup water
• 1 cup cake flour (not self-rising)
• 1/2 teaspoon baking soda
• 1/4 teaspoon salt
• 4 tablespoons unsalted butter
• 1/2 cup plus 2 tablespoons granulated sugar
• 2 large eggs
• 1/2 teaspoon vanilla extract
• 1/4 cup sour cream
• 5 ounces bittersweet chocolate, coarsely chopped
• 1/4 cup plus 2 tablespoons milk
• 1/4 cup granulated sugar
• 1/8 teaspoon salt
• 2 teaspoons vanilla extract
• 1/2 cup Bailey's Irish Cream Liqueur, divided
• 6 ounces mascarpone, softened
• 1 cup heavy cream
• 1/4 cup hazelnuts, lightly toasted and coarsely chopped
• 4 ounces bittersweet chocolate, cut into 1/2-inch chunks
• 3/4 cup heavy cream
• 2 tablespoons Bailey's Irish Cream Liqueur
• 1 tablespoon confectioners' sugar
• 2 ounces bittersweet chocolate, coarsely chopped
• Warm chocolate sauce (optional)