Boil water in a large pot. Add salt and macaroni. Cook until just tender but still firm. Do not overcook the pasta. Drain and set aside. Keep it slightly undercooked for best texture later.

Place a saucepan on medium heat. Add butter and let it melt slowly. Stir gently to avoid burning. Once melted, add flour and mix well. Cook for one minute until it smells slightly nutty.

Slowly pour in warm milk while whisking. Keep stirring to avoid lumps. Cook until the sauce thickens nicely. Add mustard powder, garlic powder, salt, and pepper. Mix everything well.

Lower the heat and add shredded cheddar and mozzarella. Stir slowly until the cheese melts completely. The sauce should look smooth and creamy. Do not rush this step for best results.

Add the cooked macaroni into the cheese sauce. Mix gently so every piece is coated well. Make sure the sauce reaches all corners for a rich and creamy bite.

Transfer the mixture to a baking dish. Sprinkle breadcrumbs on top if you like crunch. Bake in a preheated oven at 180°C for 15 minutes. This gives a golden top.