1-First Step: Get everything ready Start by heating the oven to 375°F. Bring a large pot of heavily salted water to a boil, then set out a Dutch oven, measuring cups, and a baking dish. Having everything within reach makes this baked spaghetti easier to manage, especially on a busy weeknight.

2-Second Step: Cook the spaghetti just short of done Add 1 pound of dried spaghetti to the boiling water and cook it 1 minute less than the package directions for al dente. This matters because the pasta will keep cooking once it is mixed with the sauce and baked. If you cook it too long now, it can turn soft later. Drain the spaghetti when it is ready, but do not rinse it. The starch helps the sauce cling to the noodles.

3-Third Step: Brown the sausage While the pasta cooks, melt 2 tablespoons unsalted butter in a Dutch oven over medium-high heat. Add 1 pound of Italian sausage and cook until it is no longer pink, about 5 to 7 minutes. Break it into small pieces as it cooks so every bite of Tuscan Baked Spaghetti has a little sausage in it.

4-Fourth Step: Build the sauce base Stir in the diced onion, sun-dried tomatoes, minced garlic, kosher salt, Italian seasoning, and black pepper. Cook for about 4 minutes, or until the onion softens. The pan will smell amazing at this point, and the garlic and tomatoes will start to blend into the sausage. Next, sprinkle the flour over the mixture and cook for 1 minute. This helps remove the raw flour taste and gives the sauce a smoother texture once the milk goes in.

5-Fifth Step: Make it creamy Slowly whisk in the 4 cups of milk. Pour it in a little at a time and keep whisking so the sauce stays smooth. Bring the mixture to a boil, then reduce the heat and let it simmer until thickened, about 5 minutes. At this point, the sauce should coat the back of a spoon. If it looks too thin, give it another minute or two. If it feels too thick, add a splash more milk.

6-Sixth Step: Add the spinach and pasta Stir in the baby spinach and let it wilt into the sauce. It will seem like a lot at first, but it cooks down quickly. Then add the drained spaghetti to the pot and toss until the noodles are fully coated. This is where Tuscan Baked Spaghetti really starts to come together. The noodles soak up the creamy sauce, while the spinach adds color and a fresh note that balances the sausage.

7-Seventh Step: Bake until bubbling Transfer the pasta mixture to a baking dish and sprinkle the shredded mozzarella evenly over the top. Bake at 375°F until the cheese is melted and the edges are bubbling, about 18 to 20 minutes. For a slightly deeper top, you can leave it in for the last couple of minutes until the cheese gets just a little golden. Keep an eye on it so it does not dry out.

8-Final Step: Let it rest and serve Let the Tuscan Baked Spaghetti cool for 5 minutes before serving. This short rest helps the sauce settle, so the pasta holds together better on the plate. If you like, finish with chopped fresh parsley for a bright, fresh look.