Cook pasta: Bring salted water to boil, cook macaroni until al dente. Drain and set aside.
Make roux: In a saucepan, melt butter. Stir in flour and cook 1–2 minutes until golden.
Add milk: Gradually whisk in warm milk until smooth and thickened.
Make cheese sauce: Add cheddar, mozzarella, and Parmesan. Stir until melted into a creamy sauce. Season with mustard, garlic powder, salt, and pepper.
Combine: Add cooked pasta to the sauce and mix well.
Bake (optional): Transfer to a baking dish, top with breadcrumbs mixed with melted butter. Bake at 190°C for 15 minutes until golden.
Serve: Enjoy hot and cheesy straight from the pan.