Proper Cheesy 3 Cheese Mac and Cheese: Ultimate Comfort!

Ingredients

• 1 pound (450g) elbow macaroni
• 4 tablespoons (57g) unsalted butter, plus extra for greasing
• 1/4 cup (30g) all-purpose flour
• 3 cups (720ml) whole milk
• 1/2 teaspoon salt
• 1/4 teaspoon freshly ground black pepper
• 1/4 teaspoon ground nutmeg
• 1 cup (115g) sharp cheddar cheese, grated
• 1 cup (115g) Gruyere cheese, grated
• 1/2 cup (57g) Parmesan cheese, finely grated
• 1/2 cup (50g) panko breadcrumbs (optional)
• 2 tablespoons (28g) melted butter (optional)