Chocolate Hazelnut Mousse Cake

Ingredients

• 1/4 cup hazelnuts (skins rubbed off, about 34 hazelnuts)
• 2 tablespoons granulated sugar
• 1/2 cup unbleached all-purpose flour
• 1/4 cup unsalted butter (room temperature)
• 2 tablespoons Dutch-process cocoa powder
• pinch of salt
• 1 teaspoon unflavored gelatin
• 3 tablespoons cold water
• 1/2 cup Nutella Hazelnut Spread
• 1/4 teaspoon espresso powder
• 1/2 cup mascarpone cheese
• 1 teaspoon vanilla extract
• 1 1/2 cups heavy whipping cream
• 3 tablespoons granulated sugar
• 1/3 cup heavy cream
• 4 ounces bittersweet chocolate (chopped)
• 1/4 cup toasted chopped hazelnuts for garnish