Cook pasta per directions on back of pasta package for al dente. I add 1 TBS of salt to flavor the pasta while it's cooking.
While pasta is cooking, melt butter in a large skillet over medium high heat. Once butter has melted, stir in flour with a whisk for 2 minutes. Add in garlic and cook and stir for 30 seconds.
Stir in heavy cream parmesan cheese and black pepper and stir. Allow to simmer for 8-10 minutes until sauce thickens. Stir continuously.
Turn off burner. Add in mozzarella cheese and cream cheese. Stir until cheeses have melted. Season with salt, if needed.
Drain pasta and place back in pot. Pour melted cheese mixture over pasta. Add in the diced cooked chicken. Stir to combine.
Spray a 9 x 3 baking dish with non-stick cooking spray. Pour mixture into baking dish and spread evenly. Sprinkle with additional parmesan and mozzarella, if desired.
Bake in a 350 degree preheated oven for 20-25 minutes until heated through and bubbly. Cheese will be slightly browned. Garnish with parsley, if desired.