Dacquoise Cake

Ingredients

• Meringue Japonais(layers)
• 1 1/4 cups hazelnuts, divided toasted
• 1 cup superfine sugar
• 3 tablespoons superfine sugar
• 2 tablespoons cornstarch
• 1 teaspoon cornstarch
• 6 large egg whites, at room temperature
• 3/4 teaspoon cream of tartar
• Sour Cream Ganache
• 9 ounces milk chocolate, finely chopped
• 3 ounces semisweet chocolate, finely chopped
• 1 pinch salt
• 1 cup sour cream, at room temperature
• 1 teaspoon vanilla
• Optional for Serving
• unsweetened Dutch-processed cocoa powder