Cook the pasta. Bring a large pot of well-salted water to a boil. Cook the macaroni until just al dente according to package instructions. Drain and set aside.

Make the roux. Heat a 10-inch oven-safe skillet (I used cast iron) over medium heat. Add the butter and melt completely. Whisk in the flour and cook for 1–2 minutes, whisking constantly, until smooth and lightly golden.

Build the sauce. Slowly whisk in the warmed milk until smooth. Add the garlic powder, salt, pepper, smoked paprika, and Dijon mustard. Continue cooking, whisking often, for 4–5 minutes, until the sauce thickens enough to coat the back of a spoon.

Add the cheese. Remove the skillet from the heat. Stir in the cheddar, Gruyère, and Parmesan until fully melted and smooth. Taste and adjust seasoning as needed.

Stir in the pasta. Add the cooked macaroni directly to the skillet and stir until evenly coated in the cheese sauce.

Make the garlicky panko topping. In a small skillet over medium heat, melt the butter. Add the panko, minced garlic, and salt. Cook, stirring frequently, for 2–3 minutes, until golden and fragrant. Remove from heat immediately to prevent burning.

Top the mac and cheese. Sprinkle the toasted panko evenly over the macaroni.

Bake. Bake at 375°F (190°C) for 20–25 minutes, until bubbly around the edges. If the panko topping starts to get too dark, just gently lay a sheet of foil over the top of the pan.

Finish and serve. Sprinkle with fresh parsley. Serve warm and enjoy!