Start by preparing the pasta according to package instructions, cooking it until it reaches the al dente stage. Keep in mind that the pasta will continue to cook in the oven, so don't let it get too soft at this stage. Drain it and set it aside.

In a large saucepan or Dutch oven, melt the unsalted butter over medium heat. Once it's melted, stir in the all-purpose flour, whisking it together well. Allow this mixture to cook, whisking continuously for about 2-3 minutes to create a roux.

Next, add the minced garlic to the roux. Cook it briefly just until fragrant, then pour in the heavy cream. Add in garlic powder if you wish for an extra hint of garlicky goodness. Season with kosher salt, white pepper, and one cup of the shredded Parmesan cheese. Stir everything together until it's well combined and the cheese has melted.

Let the sauce simmer on low heat for 8-10 minutes while stirring frequently. This helps it thicken and develop flavor. If it starts to stick to the bottom, just keep stirring! Once thickened, take it off the heat.

Stir in the mozzarella cheese and softened cream cheese until everything melts and becomes creamy. If you find it too thick, feel free to add a splash more heavy cream or even water for consistency. Taste the sauce, and adjust seasoning with additional salt if needed.

In the pot where you cooked the pasta, combine it with the Alfredo sauce and the diced chicken. Mix everything together until every piece of pasta is coated in that cheesy goodness!

Preheat your oven to 350°F (175°C). Transfer the pasta mixture into a 9x13 baking dish. Top it off with the remaining Parmesan cheese and sprinkle a dash of red pepper flakes for a hint of heat.

Bake in the preheated oven for 20-25 minutes. You know it’s ready when the top is starting to turn a lovely golden brown and you can see the sauce bubbling.

Once baked, remove from the oven and let it cool for a moment. You can garnish it with chopped fresh parsley if desired, and then serve warm.