Bring a large pot of salted water to a boil. Cook the fettuccine pasta until tender. Drain the pasta well and set aside. Save a little pasta water for adjusting the sauce later.

Place a large skillet over medium heat. Add butter and let it melt slowly. Stir gently to avoid burning. The butter creates a rich and smooth base for the Alfredo sauce.

Add minced garlic to the melted butter. Stir for about one minute until fragrant. Do not brown the garlic too much. Gentle cooking keeps the flavor soft and balanced inside the sauce.

Pour heavy cream and whole milk into the skillet carefully. Stir slowly with a whisk. Let the mixture warm gently for several minutes. Avoid boiling because it may change the creamy texture.

Slowly add Parmesan and mozzarella cheese while stirring continuously. The cheese melts into the sauce beautifully. Stir until smooth and creamy. Add salt, black pepper, and nutmeg for extra flavor and warmth.

Add cooked pasta into the skillet with the Alfredo sauce. Toss gently until every noodle is coated well. If needed, add a little pasta water for a silkier texture and easier mixing.

Sprinkle chopped parsley over the pasta before serving. Serve the dish warm for the best flavor and texture. Enjoy this creamy homemade Alfredo sauce with your favorite side dishes and fresh bread.