The official label instructions specify baking the dish covered in aluminum foil at 375°F (190°C) for 40 to 60 minutes, or until an internal temperature of 165°F is reached. Following these instructions to the letter, however, often leaves the pasta slightly firm in the center and the cheese on top pale and greasy. Seasoned Costco cooks use a handful of reliable modifications to elevate the results.
First, add moisture before sliding the tray into the oven. Pouring a quarter cup of whole milk or heavy whipping cream around the edges of the pasta before baking prevents the edges from drying out and helps the alfredo base retain its creamy consistency as it heats through. Keep the foil tented tightly for the first 40 minutes to trap steam, then remove the foil entirely for the final 10 to 15 minutes to let the cheddar crust bubble and brown.
Second, introduce textural contrast. The standard prepared dish lacks crunch, which can lead to palate fatigue given the extreme richness of the dairy. Topping the casserole with melted butter-tossed panko breadcrumbs, crushed butter crackers, or smoked paprika during the final 10 minutes of uncovered baking gives the dish a classic gratin finish. For a complete main dish, folding in chopped bacon, leftover Costco rotisserie chicken breast, or sautéed jalapeños transforms the side dish into a balanced family dinner.
