Preheat the oven to 375° F. Lightly butter a 9x13 inch baking dish or spray with nonstick baking spray and set aside.
Prepare alfredo sauce. Melt the butter in a saucepan over medium-low heat. Add in the minced garlic and cook for 1 minute, stirring continuously.
4 tablespoons unsalted butter, 1 tablespoon minced garlic
Whisk in the flour. Slowly whisk in the whole milk (or half and half) and heavy cream until fully incorporated.
3 tablespoons all-purpose flour, 1 ½ cups whole milk, ½ cup heavy cream
Whisk in the chicken stock, Parmesan cheese, salt, and pepper and increase heat to medium.
½ cup chicken stock, 1 cup Parmesan cheese, 1 teaspoon fine sea salt, 1 teaspoon ground black pepper
Continue to cook, whisking often, until the cheese is completely melted and the sauce has thickened slightly and is bubbling. Remove from heat.
Assemble. Place the cooked penne and diced chicken into the prepared baking dish. Pour the sauce over and toss to coat making sure the Alfredo sauce is fully incorporated.
1 pound chicken breast, 16 ounces penne pasta
Top with the shredded mozzarella and bake for 15 to 20 minutes, or until bubbly and hot.
8 ounces mozzarella cheese
Garnish with fresh chopped parsley if desired and serve immediately.
fresh parsley