Preheat the oven to 375 degrees. Cook the pasta according to the package directions. Use leftover chicken or pan fry it for a couple of minutes until done.
Melt the butter in a large pan over medium heat. Add the garlic and cook for 30 seconds. Whisk in the flour and cook for 1 minute.
Pour in the milk and cream in batches, then simmer, whisking constantly, until the sauce has just thickened. The sauce is ready when it coats the back of a wooden spoon.
Season with salt and black pepper. Remove from the heat and stir in parmesan. Stir continuously until the cheese is melted.
In a large bowl combine pasta, and chicken and pour in the sauce. Combine and mix well until all the paste is nicely coated in the sauce mixture. Grease a baking dish (I used 8x11) lightly with oil or butter.
Transfer half of the pasta mixture to the dish and top with 1 cup of mozzarella cheese. Repeat with one more layer of pasta and cheese.
Bake for 20 minutes (uncovered), until cheese is melted and golden brown. Serve with fresh parsley.