To make the Chicken and Pasta Alfredo bake, preheat the oven to 350°.
While you prepare the recipe, you can also cook your pasta simultaneously. Make sure to cook the pasta two minutes less than the package directions. Don’t forget to add salt to your pasta water.
Once cooked, drain the pasta and transfer it to a 2 ½-quart baking dish.
Top the pasta with your chicken. You can use leftover chicken, rotisserie chicken, or make chicken for the recipe.
To a skillet, you will add butter and onion over medium heat. Stir for 4 minutes.
Next, add the garlic to the skillet. Stir for 1 minute.
Then add your flour. Stir for 2 minutes.
Add the milk, heavy cream, and seasonings. Stir until creamy and thick.
Lastly, add the Parmesan cheese and 1 cup of mozzarella cheese.
Mix until fully combined and pour the sauce into the baking dish. Mix until evenly combined.
Top the casserole with the remaining mozzarella cheese. Bake uncovered for 20 minutes. Broil on high or at 500°F for 2 to 3 minutes, or until the top is golden brown.
Make sure to keep an eye on this and check it every 20 seconds, as it can turn brown very quickly.