• Preheat your oven to 350°F.
• Line a 13x9-inch baking pan with foil, ensuring the foil extends over the edges, and grease the foil.
• In a medium saucepan, cook and stir the granulated sugar and butter over medium heat until the butter is melted.
• Allow it to cool slightly.
• Add the eggs and vanilla to the sugar mixture, stirring until well combined.
• Stir in the flour, baking powder, and ground nutmeg.
• Gently fold in the chopped macadamia nuts.
• Spread the batter evenly in the prepared pan.
• Bake for 25 to 30 minutes or until the edges begin to pull away from the sides of the pan.
• Allow the bars to cool in the pan on a wire rack.
• Use the foil to lift out the uncut bars and cut them into diamond-shaped bars.

Eggnog Drizzle:

• In a small bowl, stir together 1 cup powdered sugar, 1 tablespoon eggnog, and 1/4 teaspoon vanilla extract.
• If needed, add additional eggnog, 1 teaspoon at a time, until the mixture reaches drizzling consistency.
• Drizzle the Eggnog Drizzle over the bars.
• If desired, sprinkle with grated whole nutmeg.