Stack-of-Mud Bars - Hey Recipe

Ingredients

• 15 graham crackers
• 1 stick unsalted butter (melted)
• 3 tablespoons granulated sugar
• 1 1/4 cups Nutella
• 2 large eggs (room temperature)
• 1/2 cup all-purpose flour
• 1 (3.1-ounce) bar chocolate-hazelnut (such as Ferrero Rocher®, chopped)
• 1 cup granulated sugar
• 3 tablespoons cornstarch
• 1/4 cup cocoa powder
• 1/2 teaspoon kosher salt
• 2 1/2 cups half-and-half
• 4 large egg yolks
• 2 tablespoons unsalted butter
• 4 ounces bittersweet or milk chocolate (chopped)
• 1 teaspoon pure vanilla extract
• 1 pint heavy whipping cream
• 2 tablespoons confectioners' sugar
• cocoa powder (to taste, for garnish)
• chocolate chip cookies (optional, to taste, store-bought or homemade, crushed into crumbs, for garnish)