Spaghetti baked Alfredo turns tender pasta and a silky Parmesan cream sauce into a comforting oven casserole with a lightly browned, cheesy top. A little pasta water helps the sauce cling, while a short bake brings everything together without drying it out—making this an easy, satisfying dinner for a weeknight or a casual gathering.
Ingredients
- 12 ounces dried spaghetti
- 4 tablespoons unsalted butter, divided
- 2 cloves garlic, finely minced
- 2 tablespoons all-purpose flour
- 2 cups whole milk, warmed
- 1 cup heavy cream
- 1 teaspoon kosher salt, plus more for the pasta water
- ½ teaspoon freshly ground black pepper
- ¼ teaspoon freshly grated nutmeg, optional
- 1½ cups freshly grated Parmesan cheese, divided
- 1 cup shredded low-moisture mozzarella
- 2 tablespoons chopped fresh parsley, for serving
Instructions
- Heat the oven and prepare the dish. Set a rack in the center of the oven and heat it to 375°F (190°C). Lightly butter a 9-by-13-inch baking dish or coat it with a thin layer of cooking spray. Warm the milk gently in a small saucepan or microwave; it should be warm, not boiling.
- Boil the spaghetti. Bring a large pot of water to a boil, salt it generously, and add the spaghetti. Cook for about 2 minutes less than the package’s al dente time, stirring occasionally. It will finish cooking in the oven. Before draining, reserve 1 cup of pasta water. Drain the spaghetti without rinsing it.
- Start the sauce. While the pasta cooks, melt 3 tablespoons of butter in a large saucepan over medium heat. Add the garlic and cook for about 30 seconds, stirring, until fragrant; do not let it brown. Sprinkle in the flour and whisk for 1 minute to make a smooth roux.
- Make it creamy. Slowly pour in the warm milk while whisking continuously to prevent lumps. Whisk in the cream, salt, pepper, and nutmeg, if using. Bring the mixture to a gentle simmer, then cook for 3–5 minutes, stirring often, until it lightly coats the back of a spoon. Keep the heat moderate; a hard boil can make a dairy sauce separate.
- Add the cheese. Take the saucepan off the heat. Stir in 1 cup of Parmesan a handful at a time until melted and smooth. Taste and adjust the seasoning. The sauce should be a little looser than you want the finished casserole, since the pasta will absorb some as it bakes. If it seems thick, stir in a splash of reserved pasta water.
- Combine with the spaghetti. Add the drained spaghetti to the sauce and toss until coated. If the mixture looks dry or clumps together, add reserved pasta water 1 tablespoon at a time, tossing between additions. You may not need the full cup.
- Fill and top the dish. Transfer the sauced spaghetti to the prepared baking dish and spread it into an even layer. Sprinkle the mozzarella and remaining ½ cup Parmesan over the top. Melt the remaining tablespoon of butter and drizzle it over the cheese for extra browning.
- Bake and rest. Bake uncovered for 15–20 minutes, until the edges are bubbling and the top is melted and lightly golden. For more color, broil for 1–2 minutes, watching closely so the cheese does not burn. Let the casserole stand for 5–10 minutes before serving; the sauce will settle and cling to the pasta as it rests.
Tips
- Grate Parmesan fresh. Freshly grated cheese melts more smoothly than many pre-grated varieties, which can contain anti-caking agents and turn the sauce grainy. Add it off the heat and in small handfuls.
- Undercook the pasta slightly. Spaghetti that is fully cooked before baking can become soft in the casserole. Start checking it early and drain it while it still has a firm bite.
- Keep the sauce gentle. Once the milk and cream are in, avoid a rolling boil. If the sauce thickens before the pasta is ready, loosen it with pasta water or a little warm milk.
- Plan leftovers safely. Refrigerate leftovers within 2 hours of baking, in shallow airtight containers. For best texture, store individual portions rather than leaving the casserole at room temperature to cool for a long time.
Serving Suggestions
Serve the casserole hot, topped with parsley and a little extra black pepper. A crisp green salad with a sharp vinaigrette balances the richness, while roasted broccoli, asparagus, or green beans make an easy vegetable side. Garlic bread is a familiar pairing, though crusty bread is also useful for scooping up extra sauce. For a heartier meal, add a simple protein alongside rather than crowding the baking dish.
Variations
For chicken Alfredo spaghetti, fold in 2 cups of cooked, chopped chicken before baking; rotisserie chicken works well. Add 1–2 cups of sautéed mushrooms, spinach, or broccoli for vegetables, making sure watery vegetables are cooked and drained first. You can replace the mozzarella with another 1 cup of Parmesan for a sharper finish, or use half mozzarella and half provolone for a stretchier top. Gluten-free spaghetti and a measure-for-measure gluten-free flour blend can work, but cook the pasta according to its package and check the sauce texture before assembling.
Storage and Reheating
Refrigerate the casserole or leftovers in airtight containers within 2 hours of cooking and eat within 3–4 days. Do not leave cooked pasta or dairy sauce at room temperature for longer than 2 hours, or 1 hour if the temperature is above 90°F (32°C). Reheat a portion in the microwave, covered loosely, in 30-second intervals, stirring or turning it as possible. Add a teaspoon or two of milk or water to help restore the sauce. To reheat a larger amount, cover the baking dish with foil and warm at 325°F (165°C) until hot throughout, usually 20–30 minutes depending on the amount. Reheat leftovers to 165°F (74°C), checking the center with a food thermometer. Avoid repeated cooling and reheating; warm only what you plan to eat.
Frequently Asked Questions
Can I make baked Alfredo spaghetti ahead?
For the best texture, prepare the sauce and cook the pasta shortly before baking. If you need to assemble ahead, refrigerate the covered dish promptly and bake within 24 hours. It may need extra oven time straight from the refrigerator; bake until the center is hot and bubbling, and check that it reaches 165°F (74°C). Keep the topping covered with foil at first if it browns before the center heats.
Why is my Alfredo sauce grainy?
Graininess usually comes from overheating the sauce or adding cheese while it is boiling. Remove the pan from the heat before stirring in freshly grated Parmesan, and let it melt gradually. Pre-shredded cheese can also affect the texture.
Can I use a different pasta shape?
Yes. Fettuccine, linguine, penne, or rigatoni all work. Cook any shape a couple of minutes short of its package’s al dente time, then toss it with the sauce and bake as directed. Short shapes are especially easy to portion from a casserole.
Can I freeze this casserole?
You can freeze it, but cream sauces may separate slightly after thawing, and the pasta can soften. For best results, freeze cooled portions in airtight, freezer-safe containers for up to 2 months. Thaw overnight in the refrigerator and reheat covered until steaming hot and 165°F (74°C) in the center.
How do I keep the top from getting too brown?
Bake the dish uncovered as directed, but tent it loosely with foil if the cheese darkens before the middle is hot. Broil only at the end, if needed, and stay nearby because cheese can go from golden to burnt quickly.