Cover the dish tightly with foil and bake for 25 minutes.
Carefully remove the foil and return the dish to the oven. Bake uncovered for another 20–25 minutes, or until the chicken is cooked through (165°F/74°C in the thickest part) and the stuffing on top is golden brown with the creamy sauce bubbling around the edges.
Let the casserole rest for about 5–10 minutes before serving. This helps the sauce thicken slightly and makes it easier to scoop out neat portions of chicken with a generous spoonful of the crispy stuffing on top.
If you like a little extra flavor, you can use a herbed or chicken-flavored stuffing mix, or swap in cream of mushroom soup for a more earthy taste (still keeping it to four core ingredients). For smaller households, halve the recipe and bake it in an 8×8-inch dish, checking for doneness a bit earlier. If your chicken breasts are very large, cut them into smaller cutlets so everything cooks evenly. To make ahead, assemble the casserole up to the point of adding the dry stuffing, cover, and refrigerate for up to 8 hours; when you’re ready to bake, sprinkle on the stuffing and add an extra 5–10 minutes of covered bake time since it will be starting cold. Leftovers reheat well in the oven, covered with foil at 325°F until warmed through, which makes this a great option for Sunday meal prep—cook once, and you’ve got cozy lunches ready for the first part of the week.
