Hazelnut and Chocolate Layer Cake (Hungarian Esterházy Torte)

Ingredients

For the Cake Layers

• 6 large egg whites
• ¾ cup granulated sugar
• 1½ cups finely ground hazelnuts
• ¼ cup all-purpose flour
• 1 teaspoon vanilla extract
• Pinch of salt

For the Chocolate Cream

• 6 egg yolks
• ¾ cup granulated sugar
• 1½ cups milk
• 2 tablespoons cornstarch
• 200 g unsalted butter, softened
• 150 g dark chocolate, melted
• 1 teaspoon vanilla extract

For the Topping

• ¾ cup powdered sugar
• 2–3 tablespoons lemon juice
• 30 g dark chocolate, melted
• 2 tablespoons apricot jam

For Decoration

• ½ cup finely chopped hazelnuts