Preheat oven to 350℉ (175℃) and lightly butter a 2-quart casserole dish.
Bring a large pot of water to a rapid boil. Salt the water well and then add 8 ounces dried pasta. Cook for 1 minute less than the package suggests. Drain the pasta, but do not rinse. Set aside to add to the casserole.
In a large saucepan, melt ¼ cup unsalted butter over medium-high heat. Whisk in ¼ cup all-purpose flour to form a thick paste (a roux) and cook for 1 minute to cook off the raw flour taste.
Add in ½ cup dry white wine (or additional chicken stock), while whisking, and allow the mixture to come to a boil. Cook off the alcohol for 1 minute.
Slowly whisk 1½ cups low-sodium chicken stock into the mixture, adding a little bit at a time to incorporate. Season with 1 tablespoon fresh thyme leaves, 1 teaspoon kosher salt, and 1 teaspoon black pepper. Bring the mixture to a boil, and then reduce the heat to a medium-low simmer.
While simmering, add 1 cup milk and ½ cup Parmesan Cheese to the sauce, and cook for 3 to 5 minutes, whisking occasionally, until the sauce has thickened and warmed through.
In a large mixing bowl, combine the cooked pasta, prepared sauce, and 2 cups cooked chicken together. Pour into the prepared casserole pan. Top with additional parmesan cheese if desired.
Bake for 20-25 minutes until the top of the casserole is browned and the dish is fully warmed through.
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Notes
Dry White Wine: Select a dry wine like Sauvignon Blanc or Pinot Grigio or omit the wine and use all chicken stock.Chicken: Use any cooked chicken or cooked turkey for this casserole. Thyme: Do not use ground thyme as it will overwhelm the casserole. Storage Directions: Store leftover the cooled casserole in an airtight container in the refrigerator for up to 3 days.Preparing in Advance: Assemble the casserole up to baking. Allow to cool and store in a large freezer gallon-sized bag or in a disposable casserole pan. Freeze for up to 3 months. To cook from frozen, defrost overnight in the refrigerator. Place into a greased casserole dish (if frozen in a storage bag) and bake at 350℉ covered for 1 hour and then uncover and bake for 20-30 minutes until the dish is bubbly and warmed through.