Fill a large pot with water, adding a generous pinch of salt, and bring it to a rolling boil over high heat. Once boiling, add fettuccine pasta and cook according to package instructions, typically about 10-12 minutes, until al dente. Drain the pasta using a colander and set it aside.

In a large skillet, melt butter over medium heat. Once the butter is bubbly and golden, add minced garlic, sautéing it for about 1-2 minutes until fragrant.

Pour in heavy cream and milk into the skillet, bringing the mixture to a gentle simmer. Stir regularly for about 4-5 minutes.

Gradually whisk in Parmesan cheese, allowing it to melt into the sauce for about 3-4 minutes, adjusting the consistency with milk if needed.

Season your Alfredo mixture with salt and black pepper to taste, stirring well to ensure even distribution.

Add sliced cooked chicken to the skillet, gently stirring to combine until heated through, about 2-3 minutes.

Carefully toss the drained fettuccine pasta into the Chicken Alfredo sauce, using tongs to combine thoroughly for about 2 minutes.

Transfer the creamy Chicken Alfredo fettuccine to plates, serve hot alongside garlic bread, and sprinkle with fresh parsley.