Opera Cake

INGREDIENTS

• 3/4 stick (6 tablespoons) unsalted butter
• 2 teaspoons instant-espresso powder
• 1/2 cup plus 1 tablespoon water
• 1/4 cup plus 1 tablespoon water
• 1 tablespoon granulated sugar
• 2 large egg yolks
• 7 oz fine-quality bittersweet chocolate (not unsweetened; preferably 70 to 71% cacao), coarsely chopped
• 3 tablespoons cake flour (not self-rising), sifted after measuring, plus additional for dusting pan
• 1/8 teaspoon cream of tartar
• 6 tablespoons granulated sugar
• 1/8 teaspoon salt
• 1/2 cup granulated sugar
• 1/2 cup confectioners sugar, sifted after measuring
• 1 teaspoon instant-espresso powder
• 2 tablespoons unsalted butter, melted, foam discarded, and butter cooled
• 1/4 cup Cognac or other brandy
• 2 whole large eggs at room temperature for 30 minutes
• 1 stick (1/2 cup) unsalted butter, cut into 1/2-inch cubes and softened
• 2 large egg whites at room temperature for 30 minutes
• 1 cup almond flour (3 1/2 oz) or 2/3 cup blanched whole almonds (see cooks' note, below)