Chocolate Macaroons with Orange Ganache

INGREDIENTS

• 3 1/2 ounces bittersweet chocolate (do not exceed 61% cacao), finely chopped
• 1/8 teaspoon ground allspice
• 1/2 teaspoon ground cloves
• 1/8 teaspoon kosher salt
• 1/3 cup plus 3 tablespoons egg whites (from about 3 large eggs), room temperature, whisked to loosen
• Gold dust (optional)
• 1/2 cup heavy cream
• 1/4 cup sugar
• 2 cups powdered sugar, divided
• 1 tablespoon finely grated orange zest
• 3 tablespoons natural unsweetened cocoa powder
• 2 tablespoons (1/4 stick) cold unsalted butter, cut into 1/2" cubes
• 1 1/4 cups slivered almonds