1-First Step: Cook the pasta Bring a large pot of water to a boil and salt it well. Add the 1 pound of dried spaghetti noodles and cook until just shy of al dente, usually 1 to 2 minutes less than the package directions. The pasta will finish cooking in the oven, so it should still have a little bite. Drain the spaghetti and set it aside. If you are cooking ahead or multitasking with family dinner, do not let the noodles sit too long after draining. Toss them lightly with a small splash of warm water if they start to stick. This keeps the strands loose and ready for the sauce.

2-Second Step: Start the Alfredo-style sauce Set a large skillet or saucepan over medium heat. Add 3 tablespoons unsalted butter and let it melt fully. Once the butter is melted, sprinkle in 3 tablespoons all-purpose flour and whisk constantly for about 1 minute. This cooks out the raw flour taste and starts the thickening base. Slowly pour in 3 cups whole or 2 percent milk while whisking to keep the sauce smooth. Then add 1 cup heavy cream. Keep whisking until the mixture looks uniform and starts to thicken, about 4 to 6 minutes. The sauce should coat the back of a spoon.

3-Third Step: Season and melt in the cheese Lower the heat to medium-low. Stir in 1/2 teaspoon garlic powder and 1 teaspoon kosher salt. Add about half of the shredded mozzarella and half of the grated Parmesan, reserving the rest for layering on top. Stir until the cheese melts into the sauce and everything looks creamy and glossy. If the sauce seems too thick, add a splash of the pasta water. If it feels too thin, let it cook another minute or two. The goal is a smooth sauce that clings to the pasta without pooling at the bottom of the baking dish.

4-Fourth Step: Combine the pasta and sauce Add the drained spaghetti to the skillet or transfer both to a large mixing bowl. Use tongs to coat the noodles evenly with the sauce. Make sure every strand gets some of that creamy Alfredo mixture. This step matters because even sauce distribution gives you a better baked result. At this point, taste a small bite and adjust salt if needed. Keep in mind that Parmesan adds saltiness, so add carefully. If you want the dish to feel extra rich, stir in another small handful of mozzarella here.

5-Fifth Step: Build the casserole Heat your oven to 375 degrees F. Lightly grease a 9 by 13 inch baking dish or another similarly sized casserole dish. Spoon half of the spaghetti mixture into the dish and spread it into an even layer. Sprinkle some of the remaining mozzarella and Parmesan over the top. Add the rest of the spaghetti on top, then finish with the remaining cheese. This layering helps create a creamy middle and a bubbly, golden top. It also keeps the bake from feeling dry.

6-Sixth Step: Bake until hot and bubbly Cover the dish loosely with foil and bake for about 20 minutes. Then remove the foil and bake for another 10 to 15 minutes, or until the cheese is melted, the sauce is bubbling around the edges, and the top looks lightly browned. If you want a deeper golden color, you can broil it briefly for 1 to 2 minutes, but watch it closely. Let the dish rest for 10 minutes before serving. This helps the sauce set a little, so the slices hold together better when plated.

7-Final Step: Garnish and serve Finish with finely chopped parsley leaves if you want a pop of color. Serve warm and spoon into bowls or onto plates. Alfredo Baked Spaghetti pairs well with a crisp green salad, roasted vegetables, or garlic bread for a complete meal.