Step 4: Cover Tightly and Bake
Cover the baking dish very tightly with aluminum foil — press the edges firmly against the sides of the dish to create a seal that will trap steam inside during baking. This trapped steam is essential to cooking the noodles properly: without it, the liquid will evaporate too quickly and the noodles on the outer edges of the dish may dry out before the center noodles have cooked through. Place the covered dish in the preheated oven and bake for 30 to 35 minutes. At the 30-minute mark, carefully lift a corner of the foil (steam will escape, so keep your hand and face away from the opening) and test a noodle from the center of the dish by pressing it with a fork or taking a bite. It should be fully tender with no remaining crunch. If the noodles are still firm, re-cover and bake for an additional 5 to 10 minutes before checking again.
Step 5: Optional Cheese Topping and Finishing
If you are adding cheese — and this is strongly recommended — remove the foil during the last 10 minutes of baking and scatter a generous layer of shredded sharp cheddar, Colby Jack, or Monterey Jack cheese evenly over the top of the casserole. Return the uncovered dish to the oven for the remaining 10 minutes until the cheese is fully melted and beginning to bubble and brown at the edges. Once the casserole is done, remove it from the oven and allow it to rest, uncovered, for 5 minutes before serving. This resting period allows the sauce to thicken slightly and settle, making it easier to serve in neat portions.
