Chocolate Hazelnut Cake with Praline Chocolate Crunch

INGREDIENTS

• 1 3/4 cups chilled heavy cream, divided
• 1 3/4 cups puffed rice cereal or crushed cornflakes
• 1 cup natural unsweetened cocoa powder
• Unsalted butter (for parchment paper)
• 1 1/2 cups sugar
• 3 1/2 ounces dark chocolate (do not exceed 72% cacao), chopped
• 3/4 cup (1 1/2 sticks) unsalted butter, room temperature
• 1 teaspoon hazelnut or vegetable oil
• 4 ounces dark chocolate (do not exceed 72% cacao), chopped
• 2 tablespoons corn syrup
• 1/2 cup brandy or orange liqueur
• 8 large eggs
• 1 cup hazelnut praline paste (reserved from praline chocolate crunch)
• 1/2 cup hazelnut butter (or ground roasted hazelnuts)
• Pinch of kosher salt
• 5 tablespoons unsalted butter, room temperature, cubed
• 4 ounces high-quality milk chocolate (such as Lindt or Scharffen Berger), chopped
• 1 1/2 cups blanched hazelnuts, toasted
• 1/4 teaspoon kosher salt
• 1 cup sugar, divided
• 1/2 cup heavy cream
• 1/4 cup roasted hazelnuts
• 1 cup all-purpose flour