Cook pasta: Bring a large pot of water to a rolling boil. Add the macaroni and cook according to package instructions, reducing the cooking time by 1 minute.

Toss in butter: Drain the pasta, return it to the pot, add the butter, and toss until the butter melts. Set aside to cool while preparing the sauce (Optional – Note 3).

Mix topping: Combine the panko breadcrumbs, melted butter, and salt. Set aside.

Preheat oven: Heat the oven to 180°C/350°F (suitable for all oven types).

Make roux: In a large saucepan or ovenproof skillet (such as a 26cm/9" Lodge cast iron skillet), melt the butter over medium heat. Add the flour and stir continuously for 1 minute.

Add milk: Pour in about 1 cup of the milk, stirring to dissolve the paste. Gradually add the remaining milk, whisking until smooth.

Add seasonings: Mix in the salt and optional seasonings.

Thicken sauce: Cook, stirring or whisking frequently, for 5 to 8 minutes until the sauce thickens to a creamy consistency. When the sauce coats the back of a wooden spoon and a clear path is drawn with your finger, it’s ready.

Add cheese: Remove from heat, add the cheeses, and stir until incorporated (the cheese does not need to fully melt).

Check salt: Taste and adjust the salt if necessary (with the recommended cheeses, additional salt may not be needed).

Assemble: Pour the sauce over the cooked macaroni in the pot. Mix quickly and then transfer to the skillet or a baking dish (Note 4). Sprinkle the breadcrumb topping evenly over the top.

Bake: Bake for 25 minutes or until the top is lightly golden. Avoid overbaking to prevent drying out the sauce.

Serve: Serve immediately, optionally garnished with fresh parsley. For the best make-ahead method, refer to the notes.